Two bombs exploded minutes apart in an Istanbul square packed with people Sunday night, killing 13 and injuring about 70 in what the city governor said was a terror attack.

Injured women walk after two explosions in Istanbul. Two bombs exploded in Istanbul overnight, leaving at least 14 people dead, and 140 others wounded, the NTV television station reported, citing the city's governor, Muammer Guler. [Agencies]

Many people were injured in the second blast after they rushed to the area to help the casualties of the first explosion in the working class Gungoren neighborhood, witnesses said. The blasts were about 10 minutes apart.

"There is no doubt that this is a terror attack," Gov. Muammer Guler told reporters. "The fact that there was a crowd in the area has increased the number of casualties," he added.

The governor said police were investigating who was behind the blasts.

CNN-Turk television, citing security sources, said police suspect Kurdish rebels may be responsible for the attack. It said intelligence reports had suggested the rebels were planning a bombing campaign in Turkish cities.

However, officials did not accuse any specific group.

"We know it is a terrorist attack, but which organization is responsible -- we don't yet have that information," Deputy Prime Minister Hayati Yazici told journalists at the scene of the attacks.

  A women, who was injured in a bomb blast, embraces her child as she is taken into an ambulance in Istanbul July 27, 2008. 13 people were killed and some 140 others wounded in twin bomb explosions in Turkish largest city of Istanbul late Sunday. (Reuters Photo)

Kurdish, leftist and Islamic militants are active in Istanbul and have carried out past bombings in the city. On July 9, gunmen believed to be inspired by al-Qaida opened fire on police guarding the U.S. consulate in Istanbul, killing three officers. Three attackers also died in a shootout with police.

Both of Sunday's blasts were in a square closed to traffic where people congregate at night.