The accident was reported at 6:24 a.m. on San Jose Avenue near the Highland Avenue overcrossing.
True said a J-Church train rear-ended an F-Market streetcar. Both were traveling inbound, toward downtown.
The operator of the F-Market and two women who were riding the J-Church were taken to a hospital, True said. None of their injuries are considered life-threatening, he said.
There were no passengers on the F-Market when the accident happened.
Bus shuttles were set up to serve J-Church riders between San Jose Avenue and 30th Street and Balboa Park. The accident was cleared at 8:35 a.m. and normal service resumed.