Explosion knocks out power across Waltham’s life sciences hub

Around 1:30 p.m. Tuesday, Waltham emergency crews responded to 42 Fourth Ave. after a reported transformer explosion caused widespread power outages across the city’s industrial and life sciences district.

The incident affected multiple buildings throughout the office park area along Third and Fourth avenues, as well as nearby streets including Smith Street, Wyman Street and Trapelo Road. Traffic signals in the area were also without power, leaving several major intersections dark and disrupting traffic.

The affected area is part of Waltham’s Route 128 corridor, home to a concentration of office and laboratory buildings supporting technology and life science companies. Many of these facilities have backup systems, and several buildings switched to generator power shortly after the outage, allowing operations to continue.

Emergency crews remained at the scene while utility workers restored service. The cause of the transformer explosion remains under investigation.