JUI chief Maulana Fazlur Rehman has condemned the terror attack in Istanbul, 24NewsHD TV channel reported on Sunday.

At least five people were killed while dozens sustained injuries in the attack.  The PDM leader showed solidarity with the people and the government of Turkey, a JUI statement said.

He expressed condolence and prayed the Almighty may rest the departed soul in eternal peace and grant courage to the bereaved families to bear the irreparable loss with fortitude. He also prayed for early recovery of the injured.

Reportedly, a strong explosion shook the busy shopping street of Istiklal in Istanbul, leaving many people dead and wounding dozens more, officials said. Police cordoned off the area, where crowds were dense on Sunday afternoon, and helicopters were flying over the city centre as sirens were sounding.

"I was 50-55 metres (yards) away, suddenly there was the noise of an explosion. I saw three or four people on the ground," witness Cemal Denizci, 57, said. "People were running in panic. The noise was huge. There was black smoke. The noise was so strong, almost deafening," he said.

Parents swept their children up into their arms as they fled the area. Istanbul Governor Ali confirms four deaths. Istanbul governor Ali Yerlikaya tweeted that four people died and 38 were wounded according to preliminary information. Authorities have given no indication of what caused the explosion.  A massive deployment of security forces equally barred all entrances, while a heavy deployment of rescue workers and police were visible.

The explosion occurred shortly after 4:00 pm (1300 GMT) in the famous Istiklal shopping street which is popular with locals and tourists. According to images posted on social media at the time of the explosion, it was accompanied by flames and immediately triggered panic, with people running in all directions. A large black crater was also visible in those images, as well as several bodies lying on the ground nearby.