The death toll from Tuesday's bomb explosion in Turkey climbed to 10 on Wednesday after three people died of their wounds.

Seven of the 10 victims were children. Fourteen people were wounded.

Turkish authorities said Wednesday they think the bomb detonated accidentally at about 9 p.m. as it was being carried to an unknown target.

"The bomb was made by hand, placed in a thermos and went off as it was being transported," the local governor's office said.

Initially authorities said the bomb was made from powerful explosives and was set off by a cellphone timer.

"Our sadness is great for the victims — many of them just children — of the terror attack in Diyarbakir," said Turkish Prime Minister Recep Tayyip Erdogan. "The information is not yet complete, but it is slowly getting clearer."

The bomb exploded Tuesday in Diyarbakir, Turkey's largest Kurdish-majority city, in the southeastern part of the country.

Authorities said the bomb went off near a park in a neighbourhood and witnesses said human remains were scattered over a wide area, including across the street.

People hurriedly went to a nearby hospital to give blood to help victims and to find out if their family members were among the dead or wounded, according to the Dogan News Agency, a privately run news operation in Turkey. 

The local governor's office said Wednesday it did not yet have any suspects and was still investigating.

Attacks against civilians are considered to be unusual although rebels seeking an autonomous homeland have been active in the southeast of Turkey for more than 20 years.

U.S. to offer help against Kurdish rebels

The attack came a day before a U.S. military envoy was to meet officials in Ankara to talk about ways of dealing with Kurdish rebels, who are said to have training camps in neighbouring northern Iraq.

Retired Air Force Gen. Joseph Ralston, the envoy, assured Turkish leaders on Wednesday that the U.S. is willing to help Turkey in its campaign against the rebels.

"We need [measures] urgently and they need to be visible so that not only the Turkish public, but the Iraqi public and the American public can see that we are serious about eliminating the threat of terrorism," Ralston told a news conference.

Ralston expressed sympathy with the victims of the bombing on Tuesday.

The bombing was the deadliest single attack since a blast blamed on the militant group al-Qaeda that killed 58 people in 2003.

Authorities estimate that more than 37,000 people have died in fighting since the Kurdistan Workers Party, known as the PKK, began its campaign for autonomy in Turkey in 1984.

With files from the Associated Press