CHICAGO (CBS) — Exhausted ComEd workers are back in Chicago, after spending a month helping restore power in Puerto Rico in the wake of Hurricane Maria.

The 72 ComEd linemen and support workers arrived on a charter flight at O’Hare International Airport on Monday. During their month in Puerto Rico, they visited some of the areas hit hardest by Hurricane Maria in September.

They were part of a larger contingent of Exelon utility workers who helped restore power to more than 7,000 residents in mountainous areas of Puerto Rico over the past 30 days.

The workers said it was a rewarding experience.

“We felt kind of bad that we didn’t have enough time. We wanted to stay longer,” overhead crew leader Jason Orta said. “The way that people are living, it’s sad, but it’s inspirational.”

A second group of ComEd workers left for Puerto Rico on Monday. Several remote towns in the mountains were still without electricity six months after the hurricane.