An explosion has killed at least 17 people and injured more than 40 at a textile firm's premises in a suburb of Istanbul, Turkish officials say.
Two explosions at an unlicensed fireworks factory in Istanbul have killed at least 20 people and injured dozens, Turkish officials say.
The blast caused part of a five-storey building in the western Davutpasha district to collapse.
The blasts, at just after 0930 (0730 GMT), caused part of the five-storey building in the western Davutpasha district to collapse.
Injured people were carried out of the building, but some victims are said to be still under the rubble.
Rescuers working at the scene said there were no further signs of life from beneath the rubble.
The city's governor, Muammer Guler, says it is not yet clear what caused the blast. But he ruled out terrorism.
The authorities have ruled out terrorism as the cause of the blast.
The explosion happened at about 0930 local time (0730 GMT), starting a fire in the building.
City officials said a fireworks factory had been operating in the building for more than two years without a licence.
A second blast reportedly happened just minutes later.
Mayor Kadir Topbas said the first blast sparked a fire that drew onlookers, and minutes later there was a second explosion, which is when most of the victims are thought to have been injured of killed.
"White smoke was rising into the sky from the factory as we came to the front of the building. People were running around," a witness, who identified himself as Ali, told CNN Turk television.
"White smoke was rising into the sky from the factory as we came to the front of the building. People were running around," a witness, who identified himself as Ali, told CNN Turk television.
Television pictures immediately after the blast showed survivors carrying the injured out of the building.
Witness Ahmet Unal told Anatolia news agency that the walls of the building "began to swell from the pressure".
Rescue teams continued to search through the rubble for more survivors. A number of people were taken to hospital.
"There was a big bang and the building collapsed," he said.
Mr Guler later said "right now, there is nothing linked to terror".
The surrounding streets were covered with shattered glass, metal and chunks of concrete.
Businesses in the building included textile makers and an unlicensed fireworks manufacturer, officials said.
Television pictures broadcast immediately after the blast showed survivors carrying the injured out of the building.
This is by far the most serious accident of its kind for some time, the BBC's Sarah Rainsford in Istanbul says.
A number of people were taken to hospital.
A similar explosion at a fireworks factory in 2006 killed six people but the BBC's Sarah Rainsford in Istanbul says this is by far the most serious accident of its kind for some time.
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