According to the police, the doors of the markaz were opened at around 12.30 pm.
The balloons were first seen by a villager near his house on Friday and when he found the note written in Urdu, he handed them over to the police.
The United States has slapped sanctions on Pakistan-based terrorist leader Bahawal Khan for being involved in terrorist attacks in Afghanistan and Pakistan.
At least 54 suspected militants belonging to a pro-Taliban outfit, including its spokesman, were killed on Wednesday when Pakistani fighter jets pounded their hideouts and troops clashed with the insurgents in the volatile northwest tribal region near the Afghan border.
Pakistan wants to unsettle those living in hamlets along the International Border in Jammu and Punjab, say security personnel.