This is the dramatic moment hero passers-by saved an elderly couple trapped in a sinking car in Thailand.

The locals plunged into the water after seeing the sedan hurtle into the Savarnabhumi Canal in Samut Prakan on Thursday.

They swam toward the sinking vehicle and found the occupants desperately pounding against the windows. They smashed through the glass and pulled the pensioners to safety.

Footage shows the residents carrying the shocked couple back to the shore.

The pair, aged between 70 and 80, suffered minor injuries and were taken to Chakri Naruebodindra Medical Institute for treatment.

Officers from the Bang Phli district station said the incident occurred at 5:30 pm local time.

The couple's daughter said: 'They hit an ambulance on the way home from a doctor's appointment. They were driving to Bang Phli Police Station to settle the matter but their car fell into the canal. I don't know what exactly happened or how the car got there.'

Rescuer Phirom Kaewsamlee said he was driving near the area when he was notified of the accident.

He responded to the emergency but found the couple had already been rescued by passersby.

Divers later retrieved their sunken car from the canal.

Despite being one of the wealthiest countries in Asia, Thailand suffers from chronic underinvestment in its highways and education, contributing to its poor road safety levels. Only a handful of African countries are worse.

Thailand has one of the world's worst road safety records. Ministers have set the goal of reducing fatalities from 32.7 deaths per 100,000 people to 12 per 100,000 people by the year 2027.