Police in northwestern Pakistan say about 200 militants have crossed the border from Afghanistan and attacked a security checkpoint, killing at least five police officers.

Authorities said the attack happened Wednesday in the town of Shaltalo, in the Dir tribal area along the border with Afghanistan's Kunar province. Police say fighting is ongoing.

Militants have launched a number of attacks against Pakistani security forces following the May 2 killing of al-Qaida leader Osama bin Laden.

Despite the attacks, a top Pakistani army commander, Lieutenant General Asif Yasin Malik, says the military has no plans to launch an offensive in the North Waziristan region. Pakistani media reported earlier this week that the military was planning such an operation at the request of the United States.

Also Wednesday, military officials said a helicopter carrying the head of a paramilitary force crashed into the Indus River in eastern Pakistan, with all five people onboard feared dead.

The helicopter was transporting Major General Mohammed Nawaz, who commands the force known as the Punjab Rangers, and four other people when it went down in Punjab province.

Officials said at least one body has been recovered, adding that there are no reports of survivors. Police say the cause of the crash is not clear, but that bad weather may be to blame.