Arms dump explosions rock Bulgarian capital ... then the city is struck by an earthquake

The explosions followed a fire at the complex near the village of Chelopechene on the eastern edge of the Bulgarian capital, police and civil defence officials said.

Sofia was later shaken by a 3.2-magnitude earthquake, the geological institute said. It said there was no link to the blasts. 

Blast: An explosion of gunpowder and munitions at an arms dump in Bulgaria

The tremor's epicentre was about 10 miles south of the capital and caused no casualties or damage.

The explosions continued for about eight hours. Authorities said smaller blasts were likely in the next 24 hours and urged Sofia's nearly two million citizens to stay calm.

Checks showed increased emissions of sulphur and nitrogen dioxide in the air in eastern and north-eastern suburbs but civil defence officials said human health was not threatened.

Sofia's international airport to the east of the capital was shut temporarily after debris from the blasts fell on the runway. Incoming flights were diverted to the southern city of Plovdiv.

"This morning at 6.30am a fire broke out in the area of Chelopechene and explosions followed," the emergencies ministry said in a statement.

Aftermath: Smoke and clouds of dust from a blast is seen over of gunpowder and munition depot

On Guard: Police stop a car on a road leading to the village of Chelopechene, near the arms dump

Guards at the arms complex, which is attached to a military base that is being closed down, were evacuated.

Three people from nearby villages were injured, police said. Two suffered cuts from flying glass and the third was taken to hospital with breathing difficulties.

About 2,000 people from Chelopechene and nearby villages were evacuated, while others fled their homes in panic.

"We were scared to death," Nadka Doncheva, 61, who lives in the village, told Reuters.

"All the windows are broken."

"The house was shaking. I thought it was an earthquake," a tearful woman from Chelopechene told national radio.

Overshadowed: A cyclist stops to view the black pall of smoke after an explosion rocked an arms disposal depot

Authorities are investigating the reason for the explosions.

The blasts shook apartment blocks and broke windows in eastern districts of Sofia, witnesses said. Some people dashed into the streets in panic.

"The threat is over. The danger arising from the 20 tonnes of TNT stored there has passed because it had burnt out," Defence Minister Nikolai Tsonev said after an emergency cabinet meeting.

"The explosions are declining. There is no reason for people to fear dangerous air pollution," he added.

Nato member Bulgaria is due to destroy up to 100,000 tonnes of Soviet-era munitions, officials say.

Power utilities started restoring electricity supplies to industrial plants and villages near the site of the blasts.