ISTANBUL, Turkey (CNN) -- The death toll from two deadly explosions in Turkey continued to rise early Monday as government officials confirmed 15 deaths and more than 150 injuries.
Istanbul Gov. Muammer Guler called the blasts "an act of terror," and said the devices were placed 15 meters (49 feet) from each other. The first was a stun grenade that was detonated to draw attention before the second blast went off, he said. One bomb had been placed in a trash can.
Guler said police have launched an investigation into who is responsible for the blasts. No claim of responsibility had been issued late Sunday.
The blasts happened within 10 minutes of each other in Istanbul's crowded Gungoren community about 10 p.m., Zafer Karakoc, who witnessed the explosions, told CNN Turk. Karakoc is a journalist with Turkish news agency DHA.
Dozens of firefighters and paramedics were on the scene, and several bloodied people were driven off in ambulances afterward. Glass and debris were strewn all over the brick sidewalks, and shop windows were blown out. See a map of Istanbul »
A few bodies were covered in blankets as ambulances arrived. Journalists on the scene reported seeing body parts around the square, which is closed to vehicle traffic and a central place where tourists and residents gather in the evenings.
About 150 people were taken to hospitals, said Hayati Yazici, assistant to Prime Minister Recep Tayyip Erdogan. The first blast drew people to the scene for the second explosion, increasing the number of casualties, he said.
Authorities asked residents to evacuate the heavily pedestrian, working class Gungoren neighborhood within an hour of the blast, reporters told CNN.
"This is just the type of neighborhood that ordinary people live in," journalist Andrew Finkel told CNN.
Earlier this month, at least six people, including three police officers, were killed in a shootout near the U.S. consulate in Istanbul. Two other police officers were wounded. Watch footage of the scene »
Meanwhile, Turkey -- a candidate for the European Union -- has pushed its anti-terror campaign on multiple fronts.
Tensions between Turkey and Kurdish rebels have been on the rise as Istanbul has stepped up its campaign against the Kurdistan Workers Party in response to increased attacks by the group. The rebels, known as the PKK, have waged a decades-long battle for an autonomous Kurdish region in Turkey's southeast.
And less than two weeks ago, 86 people -- including former military officials, journalists, politicians and businessmen -- were indicted on charges of being involved with an alleged terror group called Ergenekon, which aims to topple the Turkish government.
The arrests and indictments dramatize the sharp and serious political tensions between the country's Islamic-rooted ruling party -- the Justice and Development Party, or AKP -- and its outspoken critics from the nation's secularist population. Most of the people indicted are critics of the party.