The Manitowoc Fire Department was dispatched to the 2300 block of South 10th Street just after 7:00 last night after a construction crew hit a gas main.  Residents were asked to leave their homes for a short time as WPS workers labored to stop the flow of natural gas spewing into the ground. Firefighters walked up and down the street measuring the amount of natural gas in the air, as the cooler night temperatures helped disperse the gas, and keep the reading below explosive levels. No one was injured in the incident. South 10th Street has been under construction for most of the summer with the repaving project due to be completed by the end of October.