IN – Four people became ill and 10 others were evacuated after toxic levels of carbon monoxide seeped through a Highland apartment building Saturday afternoon.

NIPSCO communications manager Michael Charbonneau said 165 parts per million of the odorless gas were detected at 2740 40th St.

That’s roughly 10 times the acceptable amount.

“It’s very high and is quite dangerous,” Charbonneau said.

Utility workers traced the leak to a faulty stove in apartment 1F, Charbonneau said.

Four people went independently to Community Hospital with complaints of feeling ill.

Hospital officials, noting their common dwellings, called the Highland Fire Department, Chief Bill Timmer said.

“We responded and found a number of apartments had CO in them — about 10. We took precautions and evacuated people,” Timmer said. “We called NIPSCO and had them turn off the natural gas. Then they, the building owner, and a mechanical contractor looked for the source.”

Sometime after 3 p.m. the gas had dissipated to a non-detectable level, allowing tenants to return to their homes, Timmer said.

While officials could not identify the people affected, the chief said those exposed to carbon monoxide can get “severe headaches, nausea, flu-like symptoms and in severe cases cardiac arrest. It can be fatal. We take it very seriously.”