The Los Angeles Metropolitan Transportation Authority has reached a tentative contract agreement with its major unions that should avert a strike, Los Angeles Mayor and MTA Chairman Antonio Villaraigosa announced Tuesday afternoon.

The tentative agreements were reached after lengthy negotiations with the United Transportation Union, which represents 4,500 bus and rail operators, and the Amalgamated Transit Union, representing 2,000 mechanics and service attendants. Details of the agreements will be presented Thursday in closed session to the MTA board.

If the agreements are ratified by both the MTA board and the union members, it would mark the first time in a decade that a contract accord was reached early enough to avert a strike.