ISLAMABAD, April 15 (Xinhua) -- At least two Pakistani security personnel were killed and five others injured in an attack from across the Afghanistan border on Sunday, the military said in a statement.

The Inter-Services Public Relations (ISPR), the media wing of Pakistan army, said that the personnel of Frontier Constabulary, a paramilitary force, came under attack from the Afghanistan side when they were carrying out a routine surveillance at the Pak-Afghan border in Kurram Agency, the country's northwest tribal region.

The ISPR added that the security personnel were plugging the gaps at the border and making necessary preparations to start fencing in that area to stop unwanted infiltration from the Afghanistan side.

"Pakistani troops are exercising maximum restraint so as to avoid any Afghan civilian casualties," the statement said, adding that "military engagement is underway to defuse (the) situation."

Local administration told media that the attack was carried out from the Khost province of Afghanistan at the personnel deployed at a post in Laka Tika area of Kurram Agency.

There is no official report about the identity of the assailants. However, an investigation into the firing incident has been initiated.

Kurram Agency is one of the most sensitive tribal areas of Pakistan as it shares the border with three Afghan provinces. It was once an ideal point for militants to move across the border in the past.