NEWMARKET, Ont. -- A driver who caused a horrific crash that killed three young children and their grandfather last year was returning from his bachelor party and was so drunk that he urinated on himself and needed help standing.

Marco Muzzo, 29, pleaded guilty Thursday to four counts of impaired driving causing death and two of impaired driving causing bodily harm, before he was released on bail until his sentencing later this month.

Muzzo had faced a dozen counts of impaired driving and six more charges of dangerous operation of a motor vehicle related to the related to the Sept. 27 crash.

Anyone who pleads guilty without having a bail hearing is allowed to seek bail before sentencing, Judge Michelle Fuerst told the packed courtroom.

"This is not some sort of special privilege" granted to Muzzo, whose family is one of the wealthiest in the country, she said.

Nine-year-old Daniel Neville-Lake, his five-year-old brother Harrison, their two-year-old sister Milly, and the children's 65-year-old grandfather, Gary Neville, died after the van they were in was T-boned by an SUV in Vaughan, Ont.

The children's grandmother and great-grandmother were also seriously injured in the crash.

"A drunk driver killed my family and he admitted to it," the children's mother, Jennifer Neville-Lake, said outside court.

Neville-Lake said having the names of her children and father read out in court and associated with the charges was an emotional moment.

"Impaired operation of a motor vehicle resulting in the death of Gary Neville, resulting in the death of -- those are my babies," she said, choking back tears.

"I can't think of anything he would have to say that might remotely, even possibly, make me feel any better," she said when asked about Muzzo's expected address to the family at the sentencing hearing.

The conditions of Muzzo's $1-million bail, which his lawyer Brian Greenspan called "virtual house arrest," include a curfew, a driving ban, a ban on drinking, and no contact with the Neville-Lake family.

"There is no risk of flight, there is no risk that there is going to be any breach of bail, he's under virtual house arrest, and everyone is confident that he will abide by all terms of his release," Greenspan said outside the courthouse.

Muzzo will use the time to tie up loose ends at the family business and to seek medical treatment, his lawyer said. Greenspan would not say what condition his client has but pointed to the man's visible weight loss in recent months as a symptom.

The judge warned Muzzo that no deviation from his bail conditions would be tolerated.

Muzzo had returned from a trip to Miami on a private jet last September, landing at Toronto's Pearson airport around 3:15 p.m., according to an agreed statement of fact read in court.

"It was his bachelor party trip ... the first time he had ever flown on the corporate plane," Greenspan said.

He picked up his Jeep from the airport parking lot and drove off, court heard.

Shortly afterward, he drove through a stop sign, plowing into the driver's side of the minivan carrying the Neville-Lake family. He was speeding at the time, court heard.

A police officer called to the scene reported that Muzzo was unsteady on his feet and needed others to support him to stay upright, the statement said. The officer said Muzzo had glossy eyes, smelled of alcohol and had urinated on himself.

Court heard two breathalyzer tests taken hours after the crash showed Muzzo had 192 and 204 milligrams of alcohol per 100 millilitres of blood. Further analysis suggested he would have had as much as 245 milligrams at the time of the collision. The legal limit is 80.

It was only after he arrived at the police station that Muzzo learned the four had died, court heard.

Before the crash, Muzzo had seven non-criminal offences, including a conviction for driving with a hand-held device, according to the Ontario Ministry of the Attorney General.

Muzzo's previous offences occurred throughout the Toronto area, from Richmond Hill to Newmarket, Orillia and Mississauga, the ministry said.

The Muzzo family released a statement after their son's arrest saying they were "greatly saddened" by the tragedy, and expressed their "deepest sympathy" to the Neville-Lake family.

The family owns the drywall company Marel Contractors and is worth nearly $1.8 billion, according to Canadian Business magazine.