Updated

Afghan police have arrested a suspect in a bombing that killed five people and injured more than 30 in the southern city of Kandahar (search), a senior officer said Friday.

Provincial police chief Khan Mohammed said the suspect was nabbed in the city after Thursday's roadside explosion, which hit a taxi carrying women and children and sent shrapnel flying into other civilian bystanders.

Khan refused to give any details about the arrested man, saying a police investigation was continuing.

The bomb went off as Secretary of State Condoleezza Rice (search) visited the Afghan capital, Kabul, about 280 miles to the north, for talks with Afghan President Hamid Karzai (search). It was her first trip to the country.

On Thursday, Khan blamed the attack on rebels from renegade warlord Gulbuddin Hekmatyar's Hezb-e-Islami group, and the former ruling Taliban. A purported Taliban (search) spokesman, however, denied the hardline militia's involvement.

The bombing happened 10 days after a British consultant to the Afghan government was assassinated in Kabul, casting doubt on assertions by the Afghan government and the U.S. military that the country is becoming secure.

On Friday, plainclothes police were deployed around Kandahar — the main stronghold of the Taliban regime, ousted three years ago — and all vehicles entering the city were being checked, Khan said.

"We have tightened the security of Kandahar city. We are doing our best to stop any terrorist attack," he said.

The U.S. military said 13 people wounded in Thursday's bombing had been treated at its base in Kandahar. "Initial reports show that the patients, many of whom received shrapnel wounds, are in stable condition," it said in a statement.