An unknown device discovered near a canal prompted police patrols to descend on the area.
Residents are being urged to stay indoors after officers were called to the canal at Newton Brook, near to Church Street and Southwood Road in Newton-le-Willows , at around 1.40pm on Sunday.
Motorists are being asked to avoid the area, while an investigation into the nature of the device is carried out.
A spokesperson from Merseyside Police said: "We can confirm that a road closure is in place in Newton-le-Willows due to an ongoing incident this afternoon, Sunday 17 November.
"At 1.40pm, officers were called to the canal at Newton Brook, near to Church Street and Southwood Road, after an unknown device was located. Enquiries are ongoing to establish the nature of the device.
"A road closure is now in place on Church Street and we are asking local residents to stay indoors at this time and road users to avoid the area.
"Thanks for your patience as we deal with this incident. More updates as we have them."