Three fire engines are in attendance, one from Birchwood, one from Warrington and one from Salford
Shortly after 1pm firefighters were called to a report of an unknown substance having spilt onto the forecourt of a disused car wash on Booths Hill Road in Lymm, Warrington.
On arrival crews discovered that a quantity of the liquid had entered the drains.
They informed the Environment Agency and began carrying out investigations.
Fire crews have closed the road on Camsley Lane as a result of the spillage.
People living nearby have been advised to stay inside and keep their windows and doors closed as a precaution.
Firefighters wearing specialist suits have investigated the spillage.
It is believed that the liquid is a cleaning product.
Firefighters are awaiting a specialist company to confirm what the substance is.