BUTLER, Mo. -- Police face danger on the job every day. But there is one debilitating danger they fear that could always be lurking behind a closed door.

It's something that's been around for a while, but many small-town and rural police departments haven't dealt with it often.

The short-term effects are known to be potentially hazardous. The long-term effects are just scary, as three local officers are learning.

"I think everyone is at fault some way or another," said Officer Mark Frost, one of more than six officers who went to a home on Fort Scott Street the bitter-cold night of Nov. 25.

Authorities believed that Lyle and Justina Jennings were operating a meth lab at the house.

Chief Jim Garnett, of the Butler police department, said, "We had information that there was a lab there, but didn't believe they were actually in the process of cooking at that time."

Based on that fact, officers made the decision not to wear their protective masks, fearing that the cold air would cause them to fog up when they went charging into the house.

"Officers opted to carry their masks rather than wear them," said Chief Garnett.

"You've got to be able to see what's going on, what you're doing. If somebody's got a weapon, you've got to be able to identify who has got the weapon," Garnett said.

That one decision will forever haunt three officers from the Butler, Mo., police department.

As Cpl. Ken Rush tried to break through the front door, police said a man inside the house, Jared Webb, tried to run out the back, right where Officer Frost was waiting.

"I had to take him down at gunpoint and then had to go in and cuff him," Frost said. He was in the back door of the house, which is where the stairwell to the basement was.

In the basement, Sgt. Chad Anderson ran into Jennings. Police said that in a desperate attempt to get rid of the chemicals from the meth lab, Jennings started throwing everything into the sump pump and turned on the water.

"The chemicals mixed with the water and created a vapor," said Garnett. "Sulfuric acid, anhydrous ammonia and Coleman fuel."

Sgt. Anderson was stuck in the basement, breathing in the poisonous vapor.

Upstairs, Cpl. Rush had just broken through the front door and was breathing heavily when the fog overcame him.

And at the back door was Ofc. Frost, who said "your throat gets very irritated. Then the not being able to breathe and all that stuff -- that was the scariest part of it all."

"I can't really describe the smell, but it's one of those smells you will never forget," Frost said.

Frost spent several days in the hospital. Rush and Anderson were there for more than a week.

All three were diagnosed with chemically-induced pneumonia and heart murmurs.

For a 10-man department, that one night sidelined a third of the Butler police department, all because the officers carried their masks instead of wearing them.

As the officers later learned, the masks don't fog in extreme temperatures.

Chief Garnett said they didn't know it at the time because no one in their department has any training on how to handle meth labs. He said the funding just isn't available.

KCTV5's Jeanene Kiesling looked into how many departments deal with a lack of funding for meth lab training.

Sgt. Jason Clark, of the Missouri Highway Patrol, said the highway patrol offers free training and has since 2000.

Once Kiesling reported the information to Chief Garnett, he said that getting his officers trained will be a top priority.

"It's a lesson learned, I can tell you that much," said Frost. "But at what price was it learned?"

Frost was out of work for two months and he was in the best shape of them all. Sgt. Anderson returned to work two weeks ago. Cpl. Rush is out indefinitely.