ROCKY HILL, Conn. (WTNH) — Residents in Rocky Hill had quite the scare Tuesday morning after an apartment building needed to evacuate due to elevated levels of carbon monoxide found in the building.

Fire officials were called to 400 Cold Spring Rd. a little after 10 a.m. after a carbon monoxide detector was activated.

Investigators found dangerous levels in several apartments.

Officials said a large natural gas boiler, which a maintenance company was servicing, was the cause of the elevated levels.

Residents were about to go back inside after more than an hour.