Firefighters toiled in the rubble of the maternity and children's hospital, which partly collapsed after a gas tanker truck blew up outside.
"We have to conduct an evacuation for safety because a lot of the people are babies in the crib area," Mayor Miguel Angel Mancera told MVS Radio.Mancera said he had received a report of "a person who appears to have died, a woman" found under rubble.
He said the injured were not in serious condition and were being transferred to other hospitals.
Television images showed people with bloodied faces being carried to ambulances. Around 40 percent of the hospital was torn down, Mancera said.
