Waterloo’s university district saw its biggest St. Patrick’s Day crowd ever on Saturday, despite police warnings suggesting that officers would go further this year in an attempt to stop the unlicensed party before it could begin.

While no estimate of the crowd size was available Saturday, Waterloo Regional Police Insp. Mike Haffner said it was clear there was a “significant increase” in the number of people on Ezra Avenue from the 15,000 who showed up in 2017.

“The people that we interacted with and engaged with were respectful to our officers, however we want to be clear that we do not condone this unsanctioned, unlicensed gathering on Ezra,” he said.

While security guards outnumbered outdoor parties in the Ezra area for much of the morning, the revelry and police response both grew quickly as noon approached.

Haffner said police shut down multiple keg parties in the morning, including one which had grown to 300 people by 10:30 a.m.

Police also had to deal with multiple reports of assault, including one sexual assault, as well as intoxicated people jumping off of balconies and climbing trees.

Shortly before 10 a.m., police said, one woman was nearly struck by a vehicle after walking into traffic in the university district.

Ezra Avenue has been closed to traffic. Officers attempting to keep #spd2018 attendees on sidewalks. pic.twitter.com/2U450kFm6t — Waterloo Reg. Police (@WRPSToday) March 17, 2018

Traditionally, the student parties spill onto Ezra Avenue and police end up closing the street. Police had been hoping to crack down on the street party before it started this year, although they relented around noon and closed the road to traffic. Two dump trucks were brought in from the City of Waterloo to protect against the possibility of a vehicle intentionally being driven into the crowd.

“We want people to celebrate. We want people to have fun,” Haffnersaid at a morning media briefing.

“We’re just encouraging those that may want to come to Ezra … to go to a licensed establishment (or) enjoy the day at a private residence.”

In addition to bringing in more officers than usual for St. Patrick’s Day, Waterloo Regional Police had called in specialized crowd control support from Peel Regional Police. Haffner declined to provide the number of officers assigned to the university area.

Alcohol seized from packed vehicle headed to Ezra Avenue #SPD2018 gathering. All 6 occupants of vehicle were 18. pic.twitter.com/cbwT4BrNnn — Waterloo Reg. Police (@WRPSToday) March 17, 2018

As of 6 p.m., Waterloo Region’s paramedics had received 47 calls from the university area and transported 25 people to hospital.

“Alcohol misuse” was behind most of the calls, deputy EMS chief Kevin Petendra told reporters, and five of the 25 people hospitalized were considered to be in serious or critical condition.

The call volume was tracking along the same lines as St. Patrick’s Day 2017, although it was expected to increase as day gave way to night.

Police shared paramedics’ concerns about what would happen as darkness fell, clearing Ezra Avenue of partiers before sunset and reopening the road to vehicles. Haffner said police resources would continue to be taxes as revelers made their way to private house parties and to bars around Waterloo Region.

Dozens of officers just pushed through what was left of the crowd, clearing Ezra Ave. Students gone but lots of trash left behind. #StPatrickDay pic.twitter.com/rRhIRMh7Oa — Tina Yazdani (@TinaYazdani) March 17, 2018

In addition to patrolling the university district, police were stopping buses on their way into town to search for open liquor or other illegal activity, and breaking up unlicensed keg parties when they were reported.

Four Markham residents were arrested in Cambridge after being stopped in a vehicle that, police say, was on its way to the party in Waterloo. According to police, there were illegal drugs in the vehicle and its driver had a suspended licence.

An allegedly speeding pickup truck was stopped in Waterloo, as a result of which three University of Guelph students were charged with offences including unlawful alcohol possession, failure to use seatbelts and driving without insurance or a valid permit.

Ezra Avenue wasn’t the only street in the university district being watched closely by authorities. Shayne Turner, Waterloo’s director of municipal enforcement services, said bylaw officers were kept busy dealing with several properties on Marshall Street. Some people would face public nuisance charges as a result of those issues, he said.

Many private landlords in the university area had hired extra security for Saturday. Some landlords were also enforcing legally dubious limits on the number of guests allowed in their buildings.