The shooting took place during a party, attended by many underage people, at an Airbnb property in the city's North Side, police said. There were at least 90 rounds fired.
Officials said 10 people suffered minor injuries and at least three were taken to the hospital after the collapse, which appears to have involved several vehicles and a Port Authority bus.
Police say an incendiary device was thrown from a moving vehicle on Sunday night, damaging a parked car. A short time later, a second explosion was reported a couple of miles away.
Urban planners say cities must make it possible to return to the streets and shop without losing the safety of physical distancing.
All the victims were wearing orange wristbands and are believed to have attended the same event Saturday night, but authorities say they overdosed afterward at a private residence.
Pittsburgh International Airport has opened a 1,500-square-foot "sensory space" to help people on the autism spectrum decompress during travel. Soothing colors and private, soundproof rooms are a hit.
"Storybook Pride Prom" in Jacksonville, Fla., and Drag Queen Story Hour in Pittsburgh were canceled this weekend after both events' organizers decided they could not ensure a safe space.
A string of shootings and revelations about clergy abuse has made 2018 a hard year for the people of Pittsburgh. But some are finding new activism and hope within tragedy.
The Catholic Church has been roiled by revelations about clergy abuse in dioceses across the country in 2018. It began with a Pennsylvania grand jury report in August that detailed decades of abuse.