Police are warning residents about a string of catalytic converter thefts reported since last month in the Northwest Side Portage Park and Jefferson Park neighborhoods.

In each case, someone has cut and removed catalytic converters from parked vehicles, according to a community alert from Chicago police. The thefts have typically occurred at night or in the early morning hours when vehicles were left “parked for prolonged periods in areas accessible to thieves.”

The thefts happened:

Between 6 p.m. Nov. 20 and 9 a.m. Nov. 21 in the 5300 block of West Lockwood;

Between 6 p.m. Nov. 21 and 10 a.m. Nov. 22 in the 4900 block of West Cuyler;

About 4 a.m. Nov. 21 in the 5300 block of West Berenice;

Between 7:30 p.m. Nov. 30 and 11:45 a.m. Dec. 1 in the 5500 block of West Berenice;

About 2:20 p.m. Dec. 1 in the 6000 block of West Warwick;

About 8 a.m. Dec. 2 in the 5600 block of West Lawrence; and

About 1 p.m. Dec. 3 in the 5800 block of West Montrose.

Anyone with information was asked to call Area North detectives at (312) 744-8263.