Police are praising a nine-year-old boy's "unbelievable act of bravery" after he called 911 to notify police that he was riding in a van while his mother was driving drunk.

The incident took place in the King Township area, north of Toronto, around 4:30 p.m. ET on Wednesday, York Regional Police said.

An unbelievable act of bravery as 9yr old calls 9-1-1 to report his mom drinking and driving, while he's in the van <a href="https://t.co/aXtfjVKF2g">https://t.co/aXtfjVKF2g</a> —@YRP

Police received a 911 call that sounded as if it was coming from a car, though nobody spoke. When 911 operators called the number back, a boy answered and told them he was in a van with his mom, who had been drinking.

The boy was "clearly scared, clearly shaken up by what was going on," said Const. Andy Pattenden, who added the 911 call was "very disturbing to listen to."

At first the boy was "hysterical," Pattenden said, but the 911 operator managed to calm him down and the boy provided "excellent" information about where he was, what the van looked like and where he lived.

"Eventually his mother got on the phone telling police that she just had one drink," police said, noting it's still unclear if the phone belonged to the woman or child.

The 911 operator implored the woman to pull over, but that advice was ignored, Pattenden said,

Police said they have some details about how the woman was driving, but won't release them as the case is now before the courts.

York Regional Police allege an impaired woman continued driving for 10 minutes after her son alerted 911. (Google) Officers managed to pull the vehicle over in Newmarket, about a 10-minute drive from where the boy called 911. The 52-year-old woman was arrested immediately.

At the police station, she allegedly blew more than twice the legal limit for alcohol and was charged with impaired driving offences. The woman has since been released from custody, Pattenden said.

The boy, who was unharmed, was turned over to his father. Police said the Children's Aid Society has also been notified.

Pattenden told CBC News Network he's never encountered a case like this before.

"It is heart-wrenching," he said.

"We've had some real tragedies on the roads in York Region this year as a result of drinking and driving … maybe this nine-year-old boy prevented another tragedy."

Police said anyone who believes a motorist is drunk or on drugs should contact 911 immediately, as police consider impaired driving a crime in progress.

The police force also said impaired driving appears to be a growing problem in the area.

York Regional Police have laid more than 1,500 impaired driving charges this year, compared to 1,384 at the same time in 2014.