Ezra Avenue shut down shortly before noon Sunday as thousands filled the Waterloo street for a outdoor St. Patrick’s Day party.

One London driver was charged after police found open alcohol in their vehicle at 8:45 a.m.

Another designated driver received a 7-day suspension for stunt driving after officers found six passengers inside and one more in the trunk of the car.

Officers responded to several incidents where rocks and bottles were thrown in the crowd.

"We have been very disappointed with some of the behaviours that have been displayed by some of the people in attendance," said Ashley Dietrich, a public information officer with Waterloo Regional Police. "We have received reports of people hanging out the windows and climbing trees."

There were also multiple injuries from people slipping and falling on the ice.

One of them was a police officer, who was then taken to hospital.

Last year there were 69 calls for paramedics throughout the day.

Compare that to this year, where there were 41 calls by 3 p.m. in the Ezra Avenue neighbourhood. Of those, 18 were taken to hospital for further treatment. Most of the injuries were due to alcohol and drug misuse, and the remainder for injuries due to falls, fractures and head injuries.

"The crowd size is significant," said Kevin Petendra, the Deputy Sergeant for Region of Waterloo Paramedic Services. "It's delaying our response to patients."

Firefighters were also kept busy throughout the day.

They said they responded to 18 calls for assistance, though most were from people trapped in elevators. That problem, said firefighters, was from having too many people inside.

Despite the efforts of police, emergency workers and the community to curb the unsanctioned event, the party continues to draw a huge crowd.

Last year approximately 22,000 people came out to Ezra Avenue.

“St. Patrick’s Day is one of our largest operational events of the year,” said Dietrich.

They won't have an estimate on the crowd size until later in the week but estimate that it will be the same or even more than the previous year.

This was the first time that Bricker Avenue also had to be closed due to the crowd size.

And these illegal events can be costly.

Waterloo Regional Police told CTV last year that the total amount to ensure public safety added up to $1 million.

A task force was created last April to address the impact of unsanctioned events like the Ezra Avenue party.

They’re expected to present their recommendations to council in the fall.