LOWELL — State officials are asking the public to avoid Interstate 495 in Lowell due to a police investigation that has closed both sides of the highway during the evening rush hour, after what witnesses say was a shooting that resulted in a person dying at a shopping plaza in Berlin.

In a post on X at 4:35 p.m. Tuesday, the Massachusetts State Police called it “an ongoing law enforcement investigation.”

A few minutes earlier, the Massachusetts Department of Transportation announced a temporary closure of I-495 northbound and southbound in Lowell “due to police activity in the area,” and advised drivers to “seek alternative routes and avoid the area if possible.”

WCVB reported that police also blocked off the Boylston Street overpass to traffic, and the station’s helicopter footage showed several police vehicles stopped in the northbound lanes near a silver pickup truck parked on the grassy median. State troopers appeared to be in a standoff with a suspect, with guns drawn, the station reported. They also reported a strong police presence at the Shops at Highland Commons on the Hudson/Berlin line.

A section of the parking lot near the Fit Factory and Mooyah burger place at the plaza was cordoned off with police tape and police had two shade covers set up. A witness from the area said a person had been shot in the head and killed.

A worker at the Fit Factory said someone had been shot and killed in front of the gym, but they had not been in the gym at all. “Some people saw something, but no one really knows what’s going on,” the person said.

Berlin Police posted on their Facebook page that they responded to the Highland Commons parking lot at 3:30 p.m. for a report of an assault in progress, and were told as they approached that shots had been fired. They said there was no ongoing threat to the community, but that they were investigating the incident along with the state police, and referred all questions to the Worcester County District Attorney’s office, which usually is done when there is a death involved.

Other published reports indicated police were asking people not to gather on the overpasses to I-495, as there was a firearm involved and they could be putting themselves at risk.

According to MassDOT, northbound traffic on I-495 is being diverted at Exit 89 (Route 3), while southbound traffic is being diverted at Exit 92 (Route 38). Temporary signs and message boards are being deployed to advise drivers to seek alternate routes, and those traveling through the area should expect delays.

Massachusetts State Police announced at 7:27 p.m. that the southbound side of Interstate 495 had reopened. And MassDOT announced just past 8 p.m. that one lane had reopened on 495 north, but two were still closed at that time.

This is a developing story.