A police officer's cruiser was struck by an alleged drunken driver in Northampton after the officer had stopped to investigate an unrelated crash, police say.

The incident began shortly before 2 a.m. Saturday when Southampton Town police responded to a single-car crash on County Road 51. Police say a 38-year-old Manorville man driving a Toyota Prius had veered off the road, swiped a guardrail, crossed the median into oncoming lanes, and then crashed into a tree.

The Prius was found laying on its side with its roof crushed against the tree. The victim was extricated from the vehicle and airlifted to Stony Brook University Hospital. His identity has not been released and his current condition is unclear.

Police closed County Road 51 to investigate. At around 3:30 a.m., police say their investigation was interrupted when a second vehicle, a Honda Civic, drove through the flared road closure, passed a police officer directing traffic, and collided with an unoccupied police cruiser.

The driver of the Honda, 23-year-old Lisa Rizzo, of Cutchogue, was allegedly intoxicated. She was arrested for DWI and was hospitalized to be treated for minor injuries sustained in the crash.

Witnesses are being asked to call Southampton police at 631-728-5000.

Police say County Road 51 was reopened at around 7 a.m.