'POGO': What to do if your car goes in the water

Several cars plunged into the water after a cargo ship rammed into Baltimore’s Francis Scott Bridge early Tuesday, causing the span to collapse.

If you're ever in a car that goes underwater, authorities have offered tips to increase your chances of survival. 

How to survive a sinking car 

If your car begins to take in water, first responders want you to call for help and remember POGO. It stands for Pop the seatbelt, Open the window, and Get Out.

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"Remember to pop your seatbelt first and get your children out from oldest to youngest," said Houston Fire Department Captain Beau Moreno. He adds that the oldest children can sometimes help with younger children.

In case you can't roll the window down, a window punch can help save your life. The inexpensive tools either come in the form of a keychain or a small hammer with a pointed tip.

"Don't bother with the windshield. The windshield is designed not to break," he explained.

If you do not have a window punch, Moreno says to use the heels of your shoes to kick the window open.

He also says do not turn the car off.

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If you cannot get to dry land, Moreno says, try to get on top of your car.

If you are unable to open a window, he says to remain calm and wait until the water is over the door to open it.

Baltimore bridge collapse: Several cars plug into the water 

Two people were rescued, but officials said six people were still unaccounted for as of late morning. All were believed to be part of a construction crew that was repairing potholes on the bridge.

Sonar had detected cars in the water, which is about 50 feet deep. The water temperature was about 47 degrees Fahrenheit before dawn Tuesday, according to a buoy that collects data for the National Oceanic and Atmospheric Administration.

Kevin Cartwright, director of communications for the Baltimore Fire Department, told The Associated Press that several vehicles were on the bridge at the time of the collapse, including one the size of a tractor-trailer. He called the collapse a "developing mass casualty event," though he didn’t know how many people were affected.

FOX 26 Houston contributed to this report. This story is reported from Los Angeles.