The situation takes a turn for the worse:

"Government tanks are closing in on Misrata hospital and shelling the area," said the doctor, who was briefly reached by telephone before the line died. "The situation is very serious." ... Abdul Basset, another rebel spokesman, said the shelling at Misrata hospital was continuing. "We fear a massacre. There are about 1,000 people in the hospital and most of them are in critical conditions, they can not move or run -- many amputees among them," he said. "There are also ten Filipino nurses who we lost contact with on Friday."

He added the generator supplying electricity to the hospital had been destroyed, which left the facility without power. "We call on the world to help us. God help us, God help us," he said.

The above video from Misurata on Wednesday "appears to show gunfire, sniper fire and a line of tanks in the city." Transcript here. An overnight update from AJE:

Gaddafi's tanks rolled back into Misurata under the cover of darkness and began shelling the area near the main hospital, residents and opposition fighters said, resuming their attack after their guns were silenced on Wednesday by Western air raids. The city, around 200km east of Tripoli and home to a major oil refinery, remains of the the last opposition hold-outs in the west.

Extremely graphic footage of dead and injured children in Misurata here.