Emergency crews are continuing to battle a huge fire south-west of the Ukrainian capital Kiev, following a blast at a fuel depot.
Four people were killed, including three emergency ministry employees.
The fire at the depot, next to an army base near the town of Vasylkiv, sent huge plumes of smoke over the surrounding area.
Kiev Mayor Vitaly Klitschko warned that harmful substances in the air over the city exceeded maximum allowed levels.
He urged residents with respiratory problems to limit their "exposure to the open air".
The cause of the blaze about 30km (19 miles) from Kiev is being investigated, with officials say it may have been negligence or arson.
Meanwhile, the army has been clearing a munitions storage facility, located about 50m (164ft) away, according to Oleksandr Turchynov, secretary of Ukraine's national security and defence council.
Fears it could spread
The blaze broke out on Monday evening in one tank and spread to neighbouring containers, Ukraine's emergencies ministry said (in Ukrainian).
A large explosion occurred shortly after 08:00 local time (06:00 BST) on Tuesday.
Interior Minister Arsen Avakov tweeted: "There has been an explosion at the oil depot near Vasylkiv. A huge one."
He later wrote: "Unfortunately, the bodies of three emergency ministry employees have been found."
Mr Avakov also said that the blaze was localised.
Earlier, Ukrainian officials reported the death of one person. He is believed to be a depot employee.
Of the 16 tanks on fire, eight were said to have a capacity of 900 cubic metres (32,000 cu ft) each.
Two hundred firefighters have been trying to bring the fire under control amid fears it could spread to an adjacent depot.
People in a 2km (1.24 miles) zone around the petrol containers currently on fire have been evacuated, Mr Turchynov said.
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