NEW YORK (AP) - A company that operated out of offices on the 87th floor of the World Trade Center's north tower has filed suit to get its security deposit back from the company managing the property. The suit, filed by Thor Technologies Inc. against One World Trade Center Llc is believed to be the first litigation filed in state court stemming from the Sept. 11 attack on the twin towers. The lawsuit asks for the return of a $110,000 letter of credit that the management is holding as a security deposit for Thor's tenancy in the building. It was filed Thursday in Manhattan's state supreme court. The software company is alleging the breach of a lease agreement. Robert S. Bennett, lawyer and general counsel for Thor, said that because the company is no longer a tenant at the World Trade Center, "we no longer have a duty to pay rent, or an obligation to let them hold the letter of credit as a security deposit." Bennett said his company has asked for the letter of credit, but it has not been returned. Thor did not lose any of its 42 employees in the catastrophe. Six were in the office when the plane crashed into the building, but all escaped, Bennett said. The company said it lost about $2.5 million worth of equipment in the attack, and has been operating out of temporary offices at 445 Park Avenue, at 57th Street.