Atmos Energy started looking for gas leaks after an explosion killed a 12-year-old girl in Northwest Dallas earlier this year.

They’ve found alarmingly many of them, including dozens in Oak Cliff and West Dallas, according to a recent investigation.

The Dallas Morning News analyzed data from Atmos and found the utility reported 3,100 leaks in Dallas County in the first half of 2018. The newspaper looked at 800 hazardous leaks that were most commonly caused by “stripped pipe threads, corrosion, and aging or failing parts.” Atmos began using high-tech methods of gas-leak detection after three explosions in Northwest Dallas in February.

The News’ report maps those 800 hazardous gas leaks. About 30 were in West Dallas, and dozens more were spread across the north Oak Cliff triangle between interstates 30 and 35.