KITCHENER -- Tension was elevated at a Waterloo Region COVID-19 testing site after some people waited hours for a test.

Around 10 people were still waiting in line when the testing site closed on Tuesday. They said they'd been there since 7:30 a.m. and they were upset that they wouldn't be able to get a test.

One woman said she had to take the day off and wasn't getting paid for her time. Another brought her five-year-old son and told CTV News Kitchener she's a teacher who won't be able to go back to work until they receive a negative test result. She made an appointment, but the first one available was for Sept. 30.

"We were told before 5 that we would be the last people in to get tested, but then at 5 we were told the doors are closed and everyone needs to go home," Erin Bechtel said.

Patience was running thin for some at the testing centre. Police were called to the parking lot after an argument got heated at closing time.

"There's a lot of outrage and frustration," Bechtel said. "We're all on edge because we're all missing work."

Health officials say people should only get a COVID-19 test if they're showing symptoms or have been directed to get a test by public health.

The direction comes as line ups for testing continue to grow in Waterloo Region and the entire province.

Some people seeking testing said they waited for hours at a testing site on Tuesday, only to be told to come back again Wednesday because the site had reached capacity.

The St. Mary's General Hospital assessment centre takes walk-ins as well as appointments.

"If you book an appointment, it saves you waiting in line," said Stephanie Pearsall, the COVID testing lead with St. Mary's General Hospital. "We try to book same day, but it can be two or three days out."

At the drive-thru assessment centre in Kitchener, lines begin at 4 a.m., more than three hours before it opens. People are trying to get in whenever they can.

Cambridge offers testing by appointment only, but it can take up to 24 hours to get a call back to book that appointment. People with symptoms are tested first.

Region of Waterloo Medical Officer of Health Dr. Hsiu Li Wang said people should only be going for testing if they're showing COVID-19 symptoms or they've been directed to go for a test by a public health official.

"We're also hearing about people getting a test so they can go to a party," Dr. Wang said. "Don't do that."

Anyone whose child is sent home from school due to potential COVID-19 exposure should carefully read the letter given to them.

"That letter will inform you if that child, what symptoms they have been exposed to, if it's high-risk testing, high-risk contact, whether everybody in the family needs to be tested or not," Pearsall said. "It may only be that child. They will specifically outline exactly the steps that need to be taken."

Fergus, Centre Wellington and other rural test centres are also facing long line ups. Many are concerned about what might happen as cases continue to climb and more people need or want to be tested.

"We anticipated and increased in volume definitely as school returned," Pearsall said. "But, I am not sure we anticipated this much of an increase."

Some also raised concerns about a lack of washrooms for people waiting for a test.

The plaza is also home to other businesses who are unhappy about the line ups. One business owner said it's been chaotic with people waiting in the parking lot for hours.

St. Mary's President Lee Fairclough stopped by the site on Tuesday, apologizing to people waiting in line. She said staff will be more clear in the future about how many people will get tested and who will need to come back later.

She echoed the region, asking people who don't have symptoms or haven't been told to seek a test to come back when the lines calm down.

She said the region is working on hiring more staff, finding larger spaces and expanding hours at testing sites.