BENGHAZI, Libya — A massive explosion ripped through a major weapons depot for Libyan rebels outside this rebel-held city Friday, killing dozens and possibly dealing a major blow to the ongoing battle to topple Moammar Gadhafi.
The explosion leveled nearby buildings and overturned cars in the town of Rajma and could be felt through this city. Flames shot hundreds of feet into the air.
Medical officials said the death toll was unknown but would be high. Other reports said at least 60 had been killed, including 17 firefighters who reportedly died trying to extinguish the flames.
"We've got pieces, arms and legs, so we don't know how many people were killed," said an official at the Harwadiya Medical Center, one of the facilities where casualties were rushed for treatment.
It was unknown what caused the explosion. Pro-Gadhafi warplanes had tried to bomb the depot twice in recent days, without success, and there were no reports of air attacks when the explosion occurred at about 7 p.m. local time.
Whatever its cause, the timing of the blast couldn't have been more inopportune for the rebels.
For the first time since they took control of much of eastern Libya, the rebels on Friday had gone on the offensive, seizing the key oil town of Ras Lanouf on Libya's coastal highway, and moving their front line 70 miles to the west in what appeared to be the first step in a long-promised march to Tripoli, where Gadhafi forces are in firm control.
Whether the rebels would be able to continue their westward movement without the depot was unclear. On Wednesday, the depot had been a primary source of arms for the ragtag rebel army that rushed from Benghazi to the port city of Brega to rebuff an assault by Gadhafi loyalists.
In the west, Gadhafi forces continued their siege of rebels in Zawiya and Misrata as the battle for control of Libya became a two-front war.
In Zawiya, Gadhafi forces blocked injured rebels from entering a hospital. In Misrata, residents finally gained enough ground to recover the body of a fighter killed four days ago.
Fighters in both towns said they were running out of ammunition for their Kalashnikov assault rifles and other small weapons as they faced pro-Gadhafi forces equipped with tanks and artillery.
In Zawiya, residents said they faced Gadhafi forces on the south, east and west in the morning and successfully pushed them back. But the forces came back by afternoon through the west, eventually planting themselves in front of the hospital.