Troops and police cordoned off a smoldering army depot north of the capital as crews searched Sunday for workers missing following a chain of explosions that killed at least nine people and injured hundreds.

Nine bodies have been found but 10 workers remained missing Sunday, authorities said. More than 240 people were injured, including children, officials said. More than 130 remained hospitalized.

Prime Minister Sali Berisha said the explosions in the village of Gerdec, about 6 miles north of Tirana, were an accident: blasts triggered during work to destroy excess ammunition. The chain of explosions started Saturday and continued until early Sunday, severely hampering rescue efforts.

Footage showed a ball of fire shooting up from the site, with shrapnel and shell fragments raining down on homes and cars. The blast left a massive crater at the depot.

Click here for photos.

The first blast was heard as far away as Skopje, the Macedonian capital, some 120 miles away, and prompted a brief suspension of flights at Tirana's nearby international airport. The explosion also damaged a major electricity transmission point, leaving the area without power.

About 80 people had been working on destroying ammunition at the time, Albin Mecaj, 22, who works at the depot, told The Associated Press. Witnesses said most were able to flee after the first blast.

Authorities evacuated 4,000 people from three villages and the surrounding area, with houses more than a mile away damaged by the blast. The blasts continued for some 14 hours, until 2 a.m.

On Sunday, troops and police cordoned off the still-smoldering depot as army engineers prepared to go into the heart of the blasts.

A company had been subcontracted to destroy excess ammunition, Berisha said. In the past year, about 6,000-7,000 tons of ammunition have been destroyed.

Albania has some 100,000 tons of excess ammunition stored in former army depots across the country, Defense Minister Fatmir Mediu said. NATO countries, particularly the United States, Canada and Norway, have been helping Albania destroy excess ammunition and obsolete weaponry.

"The problem of ammunition in Albania is one of the gravest and a continuous threat," Berisha said. "There is a colossal, a crazy amount of them since 1945 until now."

Berisha said he could not rule out human error but said the ammunition could have exploded spontaneously because of its age.

Accidents have occurred at ammunition dumps in Albania in the past, although Saturday's explosions were by far the worst. Three years ago, explosions at army weapon depots in southern Albania killed an army officer and injured four others.

Berisha said most of those injured Saturday suffered burns and psychological shock but at least two were in serious condition. Five people — including two young girls with severe burns and injuries — were sent to neighboring Greece for treatment. Four others were sent to Italy, he said.

In neighboring Kosovo, hundreds of people lined up at a Pristina hospital to give blood. NATO-led peacekeepers were sending blood reserves by helicopters, officials said.

Macedonia sent blood Sunday, with Macedonian Foreign Minister Antonio Milososki flying to Tirana to offer assistance and donating blood himself.