A female suicide bomber wounded at least 13 people when she blew herself up near the main mosque in the northwestern Turkish city of Bursa on Wednesday, officials said, the fifth suicide bombing in a major urban center in the country this year.

Photographs from the scene showed the severed torso of what appeared to be the bomber lying at the side of the mosque. Police ushered dazed passers-by out of surrounding streets as ambulances and forensics teams arrived.

The local governor's office said the woman was thought to have detonated a device she was wearing at 5:26 pm (9.26 a.m. EDT) near the western gate of Bursa's Grand Mosque. Health Minister Mehmet Muezzinoglu said 13 people were injured, none critically.

There was no immediate claim of responsibility.

"The attack was carried out by a suicide bomber. It is a woman," a senior government official told Reuters.

Turkey has been hit by a series of suicide bombings this year, including two in its largest city of Istanbul blamed on the Islamic State group, and two in the capital of Ankara, which were claimed by a Kurdish militant group. It has also faced attacks from far-leftist groups, mostly on police and security forces.

The Bursa attack happened a day after the United States warned American citizens in Turkey about credible terrorist threats to tourist areas.

Bursa is Turkey's fourth-largest city, an industrial hub directly south of Istanbul across the Marmara Sea. While not one of the country's biggest tourist destinations, it draws some foreign visitors with its Ottoman-era architecture.

The mosque is situated in a bustling part of Bursa on a street full of jewelry shops. The explosion came at a busy time, shortly after a funeral and afternoon prayers, broadcaster CNN Turk said.

Many of the wounded had light injuries such as cuts from shattered windows, and some have already been discharged from the hospital.

Turkey is facing multiple security threats. As part of a U.S.-led coalition, it is fighting the Islamic State group in neighboring Syria and Iraq. It is also battling Kurdish militants in its southeast, where a 2 1/2-year ceasefire collapsed last July, triggering the worst violence since the 1990s.

A suicide bombing in Istanbul's main shopping district last month killed three Israelis, two of whom held dual citizenship with the U.S., and one Iranian. A separate attack in the city's historic heart in January killed 12 German tourists.

An offshoot of the Kurdistan Workers Party militant group, meanwhile, claimed responsibility for two suicide bombings in Ankara this year that killed 66 people.