About 10 others were injured in the ghastly incident in Charsadda district, The News International quoted police as saying.
Police officer Sohail Khalid told the daily that the three suicide bombers were killed when they tried to enter the court.
“One suicide bomber blew himself at the gate,” Khalid said. “All three terrorists have been killed.”
He said three or four people have been injured in the attack. But others at the site put the number of injuries at about 10.
Gunfire was heard after one of the blasts near the gate of a sessions court located at Tangi Bazaar, Pakistani media reported.
Hospitals in Peshawar and Charsadda were put on high alert.
Pakistan Tehreek-e-Insaf member Shaukat Yousufzai said the militants came from Mohmand Agency.
In the past 10 days, over 100 people have been killed in terror attacks across Pakistan.