You'd think the flashing lights and blaring sirens would be enough to get drivers out of the way, but not always.
As the City and County of Honolulu honored workers as part of Emergency Medical Services week, they also issued an alert to drivers: You have an important job to move over.
It's a public service announcement emergency services crews hope will help save lives.
Last year crews on Oahu responded to 71,000 calls and they say it's a big problem when people don't allow the ambulance through.
EMS director Mark Rigg gives the example of a crew trying to respond to a call of a two-year-old that isn't breathing.
"You're negotiating traffic, you're negotiating road construction. Meanwhile, the dispatchers are coming back to you on the radio, informing you that the two-month-old is still not breathing and there is CPR in progress. At that point, you're stuck in traffic and nobody's moving over," said Rigg.
EMS officials say when you hear that siren, take a deep breath and figure out if you need to move to the left or right. Definitely don't stop right where you are.
"If you're in the middle of the intersection and an ambulance comes by, just continue through the intersection. Don't stop in the intersection," said Patty Duke, Honolulu EMS Chief.
For drivers who have a loved one in the ambulance or you're just in a rush, there's a message for you too.
"The worst thing they can do is tailgating the ambulance, drafting behind them. We don't know who's going to pull in front of us. You cannot see in front of our ambulance. It's that old saying, 'If we can't see you in our mirrors and you can't see us, then we don't know you're there," said Duke.