At least four people have been taken to hospital after what the Hamilton Fire Department describes as a "coal tar pitch leak" at Ruetgers Canada Inc.

Hamilton fire say they responded to a call around 2:59 p.m. of a yellowish gas coming from the raw materials manufacturer located at 725 Strathearne Ave. N.

"As a result of the leak, there was a gas, a yellowish gas that was let out and by the time our crews arrived, the leak actually stopped," said department spokesperson Dave Forster.

"What was happening was because of the strong winds we have today, it was really carrying that yellowish green smoke some distance."

Hamilton paramedics say they transported multiple patients to area hospitals.

Police were also on scene.

According to Hamilton Fire, the Ministry of Environment and Climate Change and Ministry of Labour took over the scene this afternoon.