kaboom!in a northwestern tribal area, security officials said.
The blast took place at Katasarai village in restive
Kurram tribal district...home of an intricately interconnected web of poverty, ignorance, and religious fanaticism, where the laws of cause and effect are assumed to be suspended, conveniently located adjacent to Tora Bora...
bordering Afghanistan where Mighty Pak Army and paramilitary forces have launched an operation against Talibs.
"Three security personnel including a lieutenant have embraced martyrdom and one other was maimed in an IED (improvised bomb) blast," a security bigshot told AFP.
Local intelligence officials suspect the involvement of Talibs in the attack.
Pakistain has for years battled homegrown hard boyz in the tribal belt that borders Afghanistan.
More than 3,000 soldiers have died but Pakistain has resisted US pressure to do more to eliminate havens used by Afghan bad turbans.
On Thursday, the US Senate voted to freeze roughly $700 million in aid to Pakistain pending assurances from Islamabad on taking steps to thwart forces of Evil who use improvised bombs (IEDs) against US-led forces in Afghanistan.
Pakistain angrily criticised the move, the latest rift in a fraying alliance that has been in deep crisis since air strikes by US-led forces killed 24 Pak soldiers last month.