Butler police early this morning helped nine tenants evacuate a three-story rental house that caught fire hours after it was struck by lightning.

No one was injured in the blaze that erupted as the occupants were asleep just before 3 a.m. at 415 E. Brady St., fire officials said, but the top floor and roof were badly damaged.

Fire Chief Nick Ban said the fire remains under investigation, but it appeared that a lightning storm that moved through the city more than six hours earlier was to blame.

“Lightning,” he said, “struck the rear of the house on the third floor.”

The home is divided into three apartments — one on each floor. Three tenants live in each apartment.

Neighbors heard and saw lightning hit the house about 8:30 p.m. Wednesday.

“It blew a hole through the wall,” Ban said.

The third floor tenant threw water on the fire in the wall and thought it was out.

No one called to report what happened. Meanwhile, the fire was still smoldering in the wall.

The fire call eventually came in at 2:59 a.m., authorities said. Then police were making sure everyone in the home was out.

There were no working smoke detectors inside, officials said.

“When we got there we saw the whole roof in the back was on fire,” Ban said. “It was blazing.”

A fire crew took a hose up the top of the steps and within minutes had the fire extinguished.

Damage to the house is estimated at $30,000, with another $15,000 to $20,000 in damage to the contents of the top apartment.