Cooking is the No. 1 cause of house fires, with grease fires being a particular danger.

"That's probably one of the highest percentages of cause of fire in the city of San Antonio," said San Antonio firefighter Ben Marberry.

It's instinct to put water on fire.

"Not a good idea," said Marberry.

A demonstration by the St. Paul, Minnesota Fire Department showed why it's the worst idea.

Using a 12-foot pole, the firefighter poured a cup of water into a pot of oil had become so hot, it reached the point of ignition and burst into flames.

Instantly, a monster fireball splashed up the walls and across the ceiling.

"The water turns to steam when it hits the heat," Marberry said. "Even a cup of water is 1,700 cups of steam."

It can be instinct to carry a a flaming pot to the sink. But the dramatic demonstration showed just  how much danger anyone nearby would be in.

"Certainly their clothes are apt to catch fire, or there's a possibility of getting severely burned," Marberry said.

What should you do? 

"Put a cover on it," Marberry said. If a lid isn't at hand, a cookie sheet or pizza pan will work.

"Just slide it from the side," he said. "Wear oven mitts to keep from burning yourself and just slide it into place. Turn the heat off and let it sit."

The cover should not removed for 15 to 20 minutes while the oil cools.

In case of  fire, people should get out of the house and call 911.

Another option that may help is called the Stovetop Firestop, made by a Fort Worth company

Magnets attach two canisters under a vent hood or microwave.  When flames reach the fuse, the canister drops a fire-extinguishing powder, according to the company.

The products are about $50  and $75  and can be purchased through the commercial desk at Lowe's.