At least four people were killed during a US drone strike in Pakistan's north-west tribal area of North Waziristan on Monday night, a media report said.A US pilotless aircraft fired two missiles on a car believed to be carrying suspected militants in North Waziristan, a semi-autonomous region along the Pakistan-Afghanistan border, Xinhua reported, citing Geo TV.Identities of the dead insurgents have not been determined yet.The drone kept on hovering over the area before and after the strike, causing panic among local residents.Monday night's strike was the ninth of its kind in the tribal areas of Pakistan since the beginning of this year.So far more than 55 people have been killed and many others injured in such strikes.