DETROIT – A coordinated multi-city drug bust exposed an extremely dangerous situation Wednesday inside a Detroit house where four children were living, authorities said.

Michigan State Police said they busted an operation centered around a drug more powerful than crack and heroin. Fentanyl was being made in the house on Detroit's west side, they said.

State police who raided the home on Wednesday said they found a working fentanyl lab in the basement. At the same time, a home in Livonia was raided by drug officials. It's believed that most of the dangerous opiates were sold in Livingston and Washtenaw counties.

Fentanyl: The new heroin, but deadlier

Four very small children were living in the home on Detroit's west side.

"It's crazy," neighbor Steve Geller said. "Little kids and stuff?"

A state police drug task force team raided the house on Beaverland Street, where investigators found bunches of small bundles containing the dangerous drug.

A photo from inside the house shows that a large amount of the drug was left out in the open, with nothing to prevent the children from coming into contact with it.

When police made the bust, they took the children to Shaveante Thomas' home next door. She said the children are 10, 5, 2 and a newborn.

Investigators said that when their team went into the house, they saw powder in the basement and backed out to call a hazmat team.

Fentanyl is a deadly cousin of heroin. It's 100 times more potent than morphine and can kill anyone who touches it or breathes it in.

READ: Why opioid overdose deaths seem to happen in spurts

"I would have never known he was doing that," a neighbor said.

Buckets were brought out containing what police believe is the drug. Neighbors were stunned. They said they noticed a lot of traffic at the home, but didn't expect the lab because of the number of children living there.

"That? No way, Jose," Paige Bober said.

"I'm totally shocked," Wiley Dates said.

One man was taken into custody at the home, police said.

How dangerous is fentanyl?:

Earlier report: