A University of California at Berkeley graduate sued the fast food chain In-N-Out Burger Thursday over injuries suffered when she was badly burned by a spilled cup of hot coffee last year and an employee allegedly refused to call for an ambulance.

The lawsuit filed in Alameda County Superior Court by Hedy Chen is based on legal claims of negligence and failure to come to her aid.

Chen, who graduated from UC last year, says in the lawsuit that the incident happened when she and a friend stopped an In-N-Out drive-through restaurant in Oakland on April 1, 2013.

The lawsuit says she ordered a cup of coffee and that an employee handed her an "excessively hot" beverage in a paper cup without a protective sleeve. The cup was so hot that Chen could not hold it and she dropped it onto her abdomen and thighs, which caused her to suffer excruciating pain, the lawsuit alleges.

The suit alleges she asked the employee to call 911, but the worker refused, purportedly saying that she was forbidden to do so because it was against company policy to call 911.

Chen claims the employee then gave her a bag of ice, which, according to the lawsuit, is a poor treatment for burns and can exacerbate scarring.

Chen sustained first- and second-degree burns, spent three days in a hospital and has permanent scars, according to the lawsuit.

"It's amazing that they would refuse to call 911, and then give her ice treatment which makes it worse," Chen's lawyer, Kirk Boyd, said in a statement.

The lawsuit asks for financial compensation for the injuries in an amount to be determined by a jury.

David Jung, a professor of law with UC Hastings, says there are probably 10 lawsuits at any part of the day related to hot coffee spills.

"What's unusual here is the claim that the In-N-Out Burger employee refused to call 911 after this woman was injured," Jung says.

An executive vice president with In-N-Out tells NBC Bay Area that claim is false, adding company policed is that employees are authorized and permitted to help customers and to contact 911 in case of emergency.

In-N-Out operates in California and the southwestern United States.