A motorist stopped to help free a 7-year-old boy from an overturned sport utility vehicle in a watery ditch near Polihale Beach Monday night, the Kauai Police Department said.

The boy was with his family in an SUV traveling toward the beach on a dirt road when the SUV flipped over in a ditch and came to rest partially submerged in water at about 7 p.m.

The SUV’s driver, a 41-year-old Kapaa man, was able to get his 4-year-old daughter out of the car, but the man’s 7-year-old son remained trapped, police said.

An unidentified man driving by heard the cries for help, stopped and was able to cut through the boy’s seat belt. He removed the boy and began to administer CPR, police said.

Police said the man revived the boy before paramedics and firefighters arrived.

All three family members were taken to the Kauai Veterans Memorial Hospital. The 7-year-old boy was flown to Honolulu, where he was listed in critical condition this morning.

The Kauai Police Department Traffic Safety Section is investigating the crash.