Police are investigating to see if three robberies that took place early Monday morning on the west side are related. Three armed robbers struck a Plainfield Speedway station at U.S. 40 and Ronald Reagan Parkway about 1:50 a.m. Another armed robbery was reported less than 20 minutes later at a Speedway gas station on 10th Street and Girls School Road. The third incident was reported just before 3 a.m. at an Admiral gas station on Crawfordsville Road. Police are questioning two suspects. No one was injured in the holdups.