Louisville, KY (WHAS11) - Just as the sun rose over the Comfort Suites, EMS phones were ringing. People were complaining of dizziness, severe headaches and trouble breathing.

The calls were all coming from the Comfort Suites off Blankenbaker Parkway.

James Tidwell said, “My friend came in there and said ‘wake up’, we’ve got an emergency drill. The firemen came in and said you have to leave right now.”

But this was no drill.

Jeffersontown fire responded when EMS said the calls were likely from carbon monoxide poisoning.

That’s when the fire department discovered lethal levels of carbon monoxide inside the three-story hotel.

Major Sean Dreisdach of the Jeffersontown Fire Dept. said, “When you’re talking 400 pounds per million (PPM), you’re looking at a couple of hours. You know, being exposed to 400PPM could cause death.”

The carbon monoxide leak was coming from the hotel’s hot water heater. The State Fire Marshall’s office is investigating what caused the leak.

Ten people were transported to area hospitals and at least six of them were children.

The rest of the hotel, where 78 people slept overnight, was evacuated.

James Tidwell said, “I had a severe headache. I woke up real dizzy. I was walking around, tripping over stuff, I hit a table. They were just saying, you’ve got to get out right now.”

The poisonous gas is invisible, odorless and tasteless, making it difficult to detect. Breathing it in displaces oxygen in the body and it can kill within minutes.

Rodney Raby, the Kentucky State Fire Marshall said, “Carbon monoxide is known as the silent killer. People don’t normally know they’re being exposed to it until it’s too late.”

Major Dreisdach of the Jeffersontown Fire Dept. said, “Well, it could have caused death. If you don’t have any warning to let you know... that’s why we have smoke detectors in our houses... to detect smoke and (tell us to) get out.”

This Comfort Suites did not have carbon monoxide detectors.

The hotel is closed until further notice.

In all, 17 people were treated for symptoms of carbon monoxide poisoning at area hospitals. 10 were transported by ambulance and others drove themselves.

Kosair Children’s Hospital says they treated four children and an adult, but those people are no longer in their care.

There’s no word on the conditions of others tonight.