GARDEZ, Afghanistan (Reuters) - At least six police were killed and dozens of people wounded when as many as six gunmen and a suicide bomber attacked a police headquarters in eastern Afghanistan on Sunday morning, officials said.

It took Afghan security forces most of the day to kill the last gunmen, who had barricaded themselves in a kitchen in the compound, according to police.

The attack, claimed by the Taliban, began around 6:30 a.m. (0200 GMT) when one bomber detonated a car packed with explosives at the gate of the police headquarters in Gardez city, capital of Paktia province, said Najib Danish, a spokesman for the Interior Ministry.

Around six attackers stormed the gate after the blast, with at least two quickly killed by police. The others held out against Afghan special forces that had responded to the attack, he said.

Paktia police chief Toryalai Abdani put the toll at six police killed and 12 wounded.

Doctors at the city hospital said they had received the bodies of at least five police, as well as at least 30 wounded people, including 21 civilians.

The Taliban claimed responsibility for the attack, with spokesman Zabihullah Mujahid reporting more than 100 police were killed and wounded. The Islamist group often exaggerates casualty numbers in attacks against government targets and security forces.

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Insurgent groups like the Taliban and Islamic State have launched a string of attacks across Afghanistan in recent weeks.

Islamic State claimed responsibility for a deadly attack on a mosque in Kabul on Thursday.

A massive truck bombing and later suicide attacks left hundreds dead and wounded at the end of May and beginning of June, raising political tensions for the Afghan government, which is struggling to combat rising violence and corruption.

Thousands of international troops remain in the country to train and assist Afghan security forces as well as carry out counter-terrorism missions.

American defense officials say in coming weeks they will decide whether to send between 3,000 to 5,000 more troops as requested by military commanders.