KARACHI, Nov 24: Mystery shrouded a massive blast that  took place in a flat in the Defence area on Saturday evening that left at least one man injured.

Police ruled out the possibility of terrorist activity and attributed the explosion to ‘a non-explosive chemical process’.

The blast occurred on the fourth-floor apartment of a residential building in Defence Phase VI and was heard in various parts of neighbouring areas, prompting a heavy contingent of police, Rangers and rescue workers to rush to the site.

After initial examination, police cleared the building and said they had found ‘a non-explosive chemical’ in the apartment.

“We found a chemical in the apartment which was not explosive at all,” SP Raja Umer Khattab told reporters outside the building. “There were also some glass jars in the apartment which suggest that its occupants were busy in chemical processing that went wrong and caused the explosion.”

The four occupants of the apartment along with a little girl fled after the blast. One of them was said to have been injured in the explosion, he said.

However, the version of building residents and area people left several questioned unanswered.

“After the blast, we rushed to the site and saw a blaze coming out of the flat balcony,” said a resident. “As we approached the flat, two youngsters came out and said the blast had occurred in a geyser. But they refused to allow us to enter the flat. I forcibly entered the flat and found a man badly injured and bleeding.”

He said the occupants of the flat, including the injured man, ran away with a little girl.

A woman resident of the building said she saw the men carrying arms while escaping in a black car.

“All of them were young men and had shifted to the flat a few days ago. They did not socialise with neighbours and had little interaction with them. The flat usually remained locked during day and they came there mostly at night,” she said.