MADISON, Wis. -

A carbon monoxide scare Tuesday night at a home on Madison's east side was caused by a malfunctioning water heater, according to a release.

Madison fire crews responded to a home in the 100 block of Andrew Way around 7:20 p.m. after residents reported their carbon monoxide alarm was sounding, officials said.

Crews found dangerous levels of carbon monoxide reaching 130 parts per million at the top of the basement stairs. After ventilating the home, crews found lower levels of carbon monoxide in the basement, which they determined were coming from a broken water heater, the release said.

Madison Gas and Electric shut off the heater and told the residents it should remain off until it is repaired, the release said.