Dash-cam video from the Tucson Police Department shows an officer saving the day during a medical emergency.

Sgt. Martin Espinoza was driving when he realized a woman was having a seizure behind the wheel. He knew he had to act fast.

Espinoza told KGUN 9, "When I pulled up next to her she wasn't reacting, she was looking straight ahead and didn't appear to be slowing down or staying in her lane. She was just going to continue in oncoming traffic."

Espinoza pulled his patrol car in front of the woman’s car to stop it so she wouldn’t hit anyone else. He says she was going about 20 miles per hour.

“The doors were locked and windows were rolled up. We reached inside, put the vehicle in park, turned off the ignition and then called paramedics,” said Espinoza.

The woman was treated on the scene, and no one else was injured.