NEW HAVEN, Conn. (AP) - The mayor's office in New Haven, Conn., says a steel beam collapsed at a Yale University construction site, injuring four people.

Spokeswoman Jessica Mayorga says the four were trapped when the beam fell Monday morning at the planned air conditioning center.

A Yale-New Haven Hospital spokesman says two men being treated there are in critical condition and one is in serious condition. The fourth person is being treated at the Hospital of Saint Raphael for injuries that are considered not to be life-threatening.

The federal Occupational Safety and Health Administration and New Haven officials are investigating.