About 160 people, including several Americans, were killed or injured on Saturday by a series of large explosions at an Albanian army base on the outskirts of the capital Tirana, government officials said.
The explosions are believed to have begun while three teams were dismantling munitions stored at the base.
Albania has to dismantle its obsolete Stalinist-era arsenal and modernise its armed forces to qualify it for an invitation to join the western military alliance Nato next month.
"We do not know the exact number (of casualties)," Prime Minister Sali Berisha's spokeswoman Juela Mecani told Reuters, "but we fear the worst for the three teams, each of 21 people, working there at the time. Several were US citizens."
The US embassy in Tirana told Reuters it could not confirm the presence of US military personnel at the site. A witness, Albin Mexhaj, told Albania's Top Channel Television there were 100 people at the base.
Injured people were being taken to nearby hospitals. Local media reports said most had suffered burns, concussion, broken limbs, or were hurt by flying glass and shrapnel.
Five people were reported to be in a coma. Tirana residents were rushing to hospitals to donate blood, local media said.
"Terrified people are leaving the area on foot along the highway, women and children," said a Reuters cameraman at the scene, who also described plumes of smoke and consecutive explosions from the base. "Cars with broken windows have been abandoned on the highway."
Some reports said residents from the nearby village of Gerdec had taken shelter in concrete bunkers built by late Stalinist dictator Enver Hoxha, while others fled to the hills.
The explosions were so powerful they were felt in Tirana and the seaside resort of Durres, 20km from the base.
Interior Ministry spokesman Avni Neza said army and police forces were trying to reach the area in armoured cars.
"Helicopters have not yet managed to land because the explosions continue," Neza told Reuters, adding the number of wounded had reached more than 160.
Arlinda Causholli, a spokeswoman for Tirana Airport, said windows and glass doors were shattered at the airport, a few kilometres from the base.
"We evacuated passengers from the affected area and suspended flights for around 30 minutes," Causholli told Reuters. Flights have since resumed. (Reuters)
Dozens feared dead, 160 wounded at Albania blast