Chicago Marathon organizers detail increased security after Boston bombing

The race’s 45,000 runners also will have to use clear bags for personal belongings and enter the race through designated gateways. The city is anticipating more than 1 million spectators.

The April 15 bombing in Boston killed three people and injured more than 260 others near the finish line.

Chicago police say they’ll use dogs to detect explosives and use undercover officers. Police plan to randomly check spectators who carry large bags or backpacks. Runners also won’t be allowed to leave unattended items along the route or in Grant Park.