PORTLAND, Ore. -- We hear it all the time, don’t leave pets or kids in the car when it’s hot outside.

But how fast can a car heat up? We found out, and it only took minutes before the heat inside the car was nearly unbearable.

The thermometer started at about 73 degrees inside the KGW newsroom. That changed quickly once inside the car. Less than five minutes in, and it was 96 degrees.

“What we know is that temperatures inside cars can become extremely hot very quickly,” said Dr. Alex Kitzis who works at Providence St. Vincent Medical Center.

Kitzis said it doesn't take much for cars to become dangerous.

“Even if it's 85 degrees, the car can get up to 120 degrees relatively rapidly and that can be enough to cause heat stroke and cause death,” Kitzis said.

For the next couple days it'll be much hotter than 85 degrees. Kitzis said there are heat stroke signs to look out for if an infant has been in a hot car for too long.

“They're going to be flushed, at extremes they'll have neurologic symptoms. They'll have seizure, coma. For older kids confusion,” said Kitzis.

It goes without saying, pets shouldn't be left inside a car either.

But now a new Oregon law allows a person to break a window to save a child or pet in immediate danger.

Before smashing a window, there are things you need to know. First, police say try the door handles just to make sure they're not locked. Then there are more steps.

“The law requires the person attempts to locate the owner and it also requires if the person does decide to break the window that they stay nearby,” said Sergeant Chris Burley with the Portland Police Bureau.

Burley said before doing anything, it’s a good idea to call 911 to give police a heads up.

Washington State has a similar law, but instead only police are allowed to break a window.

Back in the car, we continued to track the rising temperatures. After about 20 minutes, the thermometer inside the car was at almost 119 degrees. The iPhone being used for a Facebook Live video stopped working due to the heat inside the car.

By around 6 p.m., the temperature inside the car was up to almost 132 degrees.