The T said it is working with state and federal agencies to determine what caused a train to derail near Lechmere Tuesday.

After a Green Line derailment near Lechmere station in Cambridge sent seven people to the hospital Tuesday, the MBTA moved to replace the line with shuttles as federal and state investigations examine the cause of the incident.

The MBTA said Wednesday it is not yet clear when regular service will resume on the Green Line as crews have not yet cleared a train that derailed in Cambridge.