GENEVA, (Reuters) – A rescue ship evacuated about 800 migrants, journalists and wounded Libyans from Misrata port in heavy shelling, but was forced to depart in haste and leave hundreds of desperate civilians behind.

The Red Star One conducted the International Organization for Migration’s sixth sea rescue mission from the battlefield city after being held up for five days by shelling and mines.

“IOM team leader on the boat Othman Belbeisi reported that hundreds of Libyan civilians had also tried to board the ship in desperation to get out of Misrata. But with a limited capacity, the ramp of the boat had to be pulled up so that the ship could pull away from the dock in safety,” the IOM said in a statement.

The ship took some 700 migrants, about 20 journalists and up to 50 wounded Libyan civilians and their families from Misrata, the last major city in western Libya under rebel control, under constant siege by troops loyal to leader Muammar Gaddafi.

“Heavy shelling of Misrata in addition to mines having been laid had prevented the IOM boat from docking for five days,” the statement said. NATO minesweepers had searched the approaches of the harbor for days to clear mines.

When the ship finally docked on Wednesday morning after waiting offshore since Saturday, shelling and shooting in the port vicinity had already forced at least 1,000 migrants who had been waiting at the harbor for the ship to flee, the IOM said.

The organization, which has previously evacuated about 6,000 people from Misrata, said that this time it had less than an hour to try to evacuate as many people as possible.

“We did our best and took everyone we could in a very short time, including Libyan women and children whose relatives had been wounded,” said Belbeisi.

IOM spokeswoman Jemini Pandya said: “Stranded migrants, war-wounded and their families have to be the priority for us for evacuation.”