Jaipur, June 19 -- Three policemen were injured, two of them critically, after a speeding trailer rammed into a police patrol vehicle in Dausa district early Thursday, police said. According to police, the collision occurred during a routine night patrol in the Lalsot area, with the injured officers later being referred to Jaipur for advanced treatment. Duty officer Lakhan, and constable Sanjay both posted at Jhampada police station, sustained serious head injuries in the crash and were referred to Jaipur. Their condition is reported to be critical. The driver of the police vehicle suffered minor injuries. RPS Kailash Meena said preliminary investigations suggest the trailer driver may have dozed off while driving. "At around 3 am, a trailer coming from behind hit the police Bolero during patrol duty. The trailer was moving at high speed and appears to have gone out of control after the driver fell asleep," he said. Witnesses said the collision was so severe that both the police vehicle and the trailer plunged nearly 20 feet into a roadside ditch and overturned. With the help of a crane, both damaged vehicles were pulled out of the ditch and taken to the police station, police said. The trailer's driver and conductor also sustained minor injuries and were treated at the district hospital, police said....