Militants attack a paramilitary police checkpoint in the troubled northwestern tribal region of Pakistan, killing at least four security personnel and injuring seven others.
The attack happened in the tribal North Waziristan on Thursday and medical sources said the death toll is expected to rise.
Local security officials said tribal policemen cordoned off the area and launched an investigation into the deadly incident.
No group has yet claimed responsibility for the attack although similar incidents are usually blamed on Taliban militants.
In another incident on Thursday, two key militant commanders of Tehrik-i-Taliban Pakistan (TTP) were killed in a successful operation by security forces in the northwestern city of Peshawar.
Peshawar and several other northwestern towns have experienced a fresh spate of violence and militancy over the past few months. Militant attacks and bomb explosions have killed hundreds of people in Peshawar so far this year.
Thousands of Pakistanis have lost their lives in bombings and other militant attacks since 2001 when Pakistan entered an alliance with the US on the so-called war against terrorism, according to local media.
Thousands others have been displaced by the wave of violence and militancy sweeping across the country.
Since late 2009, there has been a surge in militant attacks in Pakistan.