Hundreds of Ukrainian firefighters battled Tuesday to keep a blaze sparked by a deadly string of fuel depot blasts from engulfing a strategic military unit outside Kiev that has Mig-29 fighter jets and rockets on site.

At least three rescue workers and a fuel stationed attendant were reported killed and several remained missing nearly a full day after the first spark set fire to an underground fuel storage facility on Monday evening.

Ukrainian Security Council Secretary Oleksandr Turchynov and Defence Minister Stepan Poltorak arrived at the scene Tuesday morning to oversee the rescue and coordinate work aimed at saving the airbase.

More than 1,500 National Guard troops sealed off the area as thick black plumes of suffocating smoke blocked the sun some 30 kilometres (20 miles) southwest of Kiev.

"The danger of the flames spreading to the military unit and the neighbouring petrol tanks has passed," Turchynov reported on Tuesday evening.

The security chief also promised to launch a criminal investigation into the design engineers who had placed a tight ring of fuel storage facilities around a military base loaded with heavy bombs and various rockets.

At least 10 people were being treated for burns and other injuries.

The lightning speed with which the flames spread to neighbouring installations and surrounding forest fuelled initial confusion among emergency workers and contradictory toll figures.

The interior ministry initially reported the evacuation of more than 2,000 people from the immediate vicinity of the blaze. Police on site later admitted that no such operation was ever conducted and that some locals had simply left on their own.

AFP reporters also saw dozens of additional firetrucks and ambulances being dispatched to the scene as new blasts sent shockwaves across Vasylkiv -- a leafy town of 40,000 that the emergencies ministry said became the scene of Ukraine's worst blaze since the 1960s.

Videos posted online showed the force of the first explosion and the heatwave it produced setting ablaze several firetrucks and ambulances that had been rushed to the scene.

A fireman wearing a silver heat-resistant suit and mask was seen running away from the disaster for his own safety.

"Everyone -- leave. Whoever is still here -- leave," one fireman said in a video.

- 'Possibility of sabotage' -

Kiev has been suffering from a dry heat spell that has seen temperatures soar towards 30 degrees Celsius (86 degrees Fahrenheit) for more than a week.

Security Council chief Turchynov said the accident most likely resulted from human error and "safety rule violations".

"But the second possibility is sabotage," he added in televised comments.

The damaged fuel depots are owned by a Ukrainian company called BRSM-Nafta that operates a large chain of petrol stations.

BRSM-Nafta spokesman Oleksandr Melnychuk told AFP that several explosive devices had been discovered near his company's storage tankers since last August.

"We view this as an attempt to put pressure on the company owner," Melnychuk said in a telephone interview.

"They wanted to nationalise (the company) -- to take it away from us."
Source: AFP