A suicide bomber blew himself up him in a busy market in northwest Pakistan on Wednesday, killing 15 people.
The blast took place close to Pakistan's border regions with Afghanistan, where Islamist militants are strong.
Quoting a police officer, NBC News reported that the attacker struck as a bus left the site.
Shad Ali, a doctor who heads the health administration in Kohat, said 15 were killed and 25 injured.
Islamist militants seeking to overthrow Pakistan's broadly pro-Western government have carried out scores of bombings in recent years, mostly against Western or government targets. The army has responded with offensives in some parts of the northwest.
On Monday, 50 people were killed in two blasts at a government compound in Mohmand, also in the border area.
A spokesman for the Pakistan Taliban, the main militant group in the northwest, claimed responsibility for that attack earlier Wednesday.