(CNN) A gas leak that forced the evacuation of some 100 people in Lawrence, Massachusetts, last week happened when road workers inadvertently closed a gas valve that should have been disabled previously, state authorities told CNN.

Friday's evacuations came a year after Lawrence and two nearby communities were hit by a string of gas explosions that killed at least one person.

Power was cut early Friday to 1,900 homes in the city, about 30 miles north of Boston, due to the most recent leak, National Grid spokesman John Lamontagne told CNN. About 80,000 people live in Lawrence.

Friday's leak happened when road workers who were checking water valves inadvertently closed a gas valve, puncturing an active main line, the Massachusetts Department of Public Utilities told CNN Monday in a joint statement with the city and Columbia Gas.

The workers had been checking water valves to prepare for road paving, the statement reads.

Read More