The bomb squad is attending an incident in Buckshaw Village near Chorley.
The alert was raised this morning after reports that a suspicious package had been delivered to Cellmark Forensics, on Ordnance Road.
A spokesman for Lancashire Police said: “We were called at around 10.15am following reports of a suspicious package at Cellmark Forensics, Ordnance Road, Buckshaw Village.
“The EOD (Explosive Ordnance Disposal) have been notified and are on route.
“As a precaution, the premises and all surrounding buildings within 100m have been evacuated and officers remain on the scene.”
The team has now arrived at the scene and removed a robot from their van.
Ordnance Road remains closed and there is a police cordon in place.
Coun Matthew Lynch, who represents Astley and Buckshaw on Chorley Council, said: “As I understand it a suspicious package has been found at the forensic lab and at the moment we have to cordon off the area.
“We have both pubs acting as holding sites for staff and I believe the Cow Shed has got some staff from Tesco there.
“At the moment they are telling everybody to avoid the area and people are stopping asking questions.
“I think there is no sense of panic, everybody is quite calm.”
Brian Brooks, 55, who works as a software engineer at Badger Office Supplies on Ordnance Road, said: “I was at my desk and an announcement came over the tannoy that everybody has to evacuate the building to go to the War Horse or the Harvester.
“I didn’t believe it at first - I thought it was a wind-up. I thought it was a fire drill.
“I saw the police and thought it was something more serious.
“People have been wandering outside, speaking to the police. People are being calm.”
Andy Watkinson, 46, of Berkshire Drive. Buckshaw Village, said: “Originally I heard Tesco had been closed. I was coming down to Tesco and Tiny Rockers.
“I though Tesco petrol station had been closed and I found out there was a company that does DNA testing and they received a suspicious package this morning.
“I thought it was going to be some ordnance on the building site because this area is well-known for its history.”
A spokesman for the War Horse pub said: “At this time the police have advised us that as we are at a safe distance they are happy for us to remain open and look after people in the area displaced by this incident.”
A spokesman for Harvester said: “We were very happy to welcome local businesses and residents into our Harvester while the police investigated the incident.
“Everyone has stayed warm and dry, we’ve had free tea and coffee flowing, and been busy serving up breakfast and nibbles to keep everyone comfortable while they waited.”
Cellmark has state-of-the-art forensic DNA testing laboratories and the building was opened seven years ago by Chief Constable of Staffordshire Constabulary, Chris Sims.
Read more stories involving the bomb squad in Lancashire.