Richardson police and fire vehicles not in service or on active calls tomorrow morning, Sept. 11, will take part in commemorating the 20th anniversary of the 9/11 attacks at 7:46 a.m., the time (per CST) when the first attack occurred. Police cars will pull over to the side of the road and fire trucks will be driven out of their stations and onto the driveway, and the vehicle lights will flash for a brief moment. Also at that time, a commemorative message will go out over Richardson police and fire radio systems, and a video will be posted on police social media.