An explosion has killed at least 17 people and injured more than 40 on Thursday at a multi-storey building in Davutpasa, a suburb of Istanbul, Turkish officials announced.

There has not been established a cause for the blast, but Governor Muammer Guller ruled out terrorism and says an investigation is under way.

“We don’t know (the cause of the explosion), we’re still looking into it,” he said according to Reuters.

The explosion occurred at about 9:30 a.m. local time, starting a fire in the building. A second blast reportedly happened just minutes later.

Local television footage showed a seriously damaged building with broken windows and surrounded by debris. They also showed at least two men lying in the street and another man with blood on his face walking nearby.

“White smoke was rising into the sky from the factory as we came to the front of the building. People were running around. I helped carry out six injured people, a witness who identified himself as Ali told CNN-Turk television.

Firefighters and ambulance crews rushed to the scene. Rescue workers continued to search through the rubble for more survivors. It seems that people was killed and injured when the building collapsed following the explosion. Most of the injured were taken to the hospital. three of them were in serious condition, Mehmet Bakar, head of Istanbul’s health authority told CNN-Turkey television.

Local media sources say business in the building included textile makers and an unlicensed fireworks manufacturer, which might have been the cause of the explosions.

The explosions shattered windows of surrounding buildings and damaged cars parked nearby as rubble and dust covered the street, television pictures showed.