Karen Grieb (Claimant) petitions for review of the decision of the Unemployment Compensation Board of Review (Board) which affirmed the referee’s denial of benefits under Section 402(e) of the Unemployment Compensation Law (Law).1
*1140The facts, as found by the Board, are as follows:
1. The claimant was last employed as a health and physical education teacher by the State College Area School District in a part-time capacity (4 days per week) at $7.40 per hour and had been so employed from 1985 and her last day of work was October 18,1999.
2. The employer’s policy, of which the claimant was aware, prohibits possessions of weapons and replicas of weapons in any school district building or on school property.
3. On September 15, 1999, the claimant violated the employer’s weapons policy by transporting three shotguns onto school property.
4. The three shotguns were visible in the backseat of the claimant’s 1991 Ford Taurus as such automobile was parked on school property and the contents therein were visible to passers by [sic].
5. The claimant is suspended without pay due to violation of the employer’s weapon policy.
6. The claimant asserts that she was moving her residence and that is the reason the guns were in her car.
Board Decision, February 11, 2000, at 1-2; Reproduced Record (R.R.) at 6a-7a.
The Board determined that Claimant was aware of State College Area School District’s (Employer) policy2 which prohibited the possession of weapons on Employer’s property and violated it without cause when she brought the three shotguns onto Employer’s property in the car she drove to work on September 15, 1999.3
Claimant contends that the Board erred when it determined she committed willful misconduct when she inadvertently drove her car onto Employer’s property at a time when it contained the three shotguns.4
Whether a claimant’s conduct rises to the level of willful misconduct is a question of law subject to our review. Lee Hospital v. Unemployment Compensation Board of Review, 139 Pa.Cmwlth. 28, 589 A.2d 297 (1991). The employer bears the burden of proving that it discharged an employee for willful misconduct. City of Beaver Falls v. Unemployment Compensation Board of Review, 65 Pa.Cmwlth. 14, 441 A.2d 510 (1982). Willful misconduct is defined as conduct that represents a wanton and willful disregard of an employer’s interest, deliberate violation of rules, disregard of standards of behavior which an employee can rightfully expect from his employee, or negligence which manifests culpability, wrongful intent, evil design, or intentional and substantial disregard for the employer’s interest or employee’s duties and obligations. Frick v. Unemployment Compensation Board of Review, 31 Pa.Cmwlth. 198, 375 A.2d 879 (1977). The employer bears the burden of proving *1141the existence of the work rule and its violation. Once the employer establishes that, the burden then shifts to the claimant to prove that the violation was for good cause. Peak v. Unemployment Compensation Board of Review, 509 Pa. 267, 501 A.2d 1383 (1985).
Initially, Claimant contends that Employer’s policy on weapons only applied to students and not to staff. The Board found that the policy prohibited the possession of weapons on Employer’s property. A review of the policy reveals that the prohibition is not limited to students, even though the disciplinary portion of the policy only addressed the discipline of students and not staff. The Board’s finding that Employer possessed a weapons policy that applied to Claimant is supported by substantial evidence.
Claimant next contends that even if she violated Employer’s policy, her inadvertent, one time violation of the policy does not constitute willful misconduct. It is undisputed that Claimant parked the vehicle on school property and that the vehicle contained three visible shotguns. It is clear that Claimant violated Employer’s work rale. The burden then shifted to Claimant to establish good cause for the violation of the work rale.
Claimant testified that she was in the process of moving her belongings to a new apartment and the “back seat [of her car] was secured with CD’s, a lot of personal belongings, clothing, lamps, things of that nature and a shotgun on the edge of the back seat and two on the floor.” N.T. at 5. Claimant testified that she loaded the car on September 14,1999, and did not plan to move the material until the next morning because it was rainy and cold and she was not scheduled at school until 11:30 a.m. However, the next morning Employer called at 6:00 a.m., to substitute for another teacher, so she drove to school and parked the vehicle in Employer’s parking lot and forgot the guns were in the vehicle. N.T. at 6-7.
Here, Claimant’s explanation, offered to satisfy her burden of proving good cause for a violation of Employer’s policy, was that she forgot the three shotguns were in the car when she drove to work and parked on Employer’s property. We agree with the Board that Claimant did not establish good cause.
Generally, unintentional, inadvertent violations of an employer’s work rules do not constitute willful misconduct. However, there is an exception to this rule where an employee’s conduct could jeopardize an employer’s effective operations or place the public at risk. United Refining Co. v. Unemployment Compensation Board of Review, 661 A.2d 520 (Pa.Cmwlth.), petition for allowance of appeal denied, 543 Pa. 721, 672 A.2d 312 (1995).
Here, Employer established the threat to public safety. Three shotguns were brought onto school property, and left in plain view in an unattended car throughout the school day. The threat to public safety and the Employer’s interest was self-evident. This Court has held in a case not involving a school district that an employee who brought a vial of gunpowder onto the employer’s premises was serious enough to be classified as inimical to the employer’s best interests and constituted willful misconduct. Prior v. Unemployment Compensation Board of Review, 52 Pa.Cmwlth. 213, 415 A.2d 940, 943 (1980).
Accordingly, we affirm.
ORDER
AND NOW, this 26th day of January, 2001, the order of the Unemployment Compensation Board of Review in the above-captioned matter is affirmed.
. Act of December 5, 1936, Second Ex.Sess., P.L. (1937), as amended, 43 P.S. § 802(e).
. Paragraph 2 of the Employer's Weapons Policy provides:
The State College Area School District [Employer] prohibits possession of weapons and replicas of weapons in any school district building, on school property, at any school sponsored activity, and in any public conveyance providing transportation to or from school or a school sponsored activity. If weapons are found in the schools, the district will take all appropriate steps to remove the weapons and carry out the relevant provisions of Act 26 of 1995.
State College Area School District Weapons Policy at 1.
. Employer informed the referee at hearing that, following Claimant's suspension, the school board voted to discharge Claimant because of this incident. However, because the arbitration concerning the discharge had not yet occurred, Employer continued to maintain Claimant in the status of a suspended employee. Notes of Testimony, December 15, 1999, (N.T.) at 8. The record does not indicate any change in Claimant’s status.
.Our review in an unemployment compensation case is limited to a determination of whether constitutional rights were violated, errors of law were committed, or essential findings of fact are not supported by substantial evidence. Lee Hospital v. Unemployment Compensation Board of Review, 161 Pa. Cmwlth. 464, 637 A.2d 695 (1994).