MINNEAPOLIS — A 2-year-old boy was killed and his 15-month-old sister was wounded after they were caught in a drive-by shooting, jangling the nerves of a city already on edge after police killed a black man with a 4-year-old in the car during a traffic stop this week.

Two-year-old Le’Vonte King Jason Jones and Mela Queen Melvina Jones were shot Friday morning as they sat in their father’s car at a north Minneapolis intersection. The boy died after the father rushed him to a hospital. The girl was shot in the leg and is in stable condition.

Witnesses said the shooting was gang-related. A police spokesman couldn’t confirm that but said the father and the attacker or attackers knew each other. No one has been arrested. Investigators said they were reviewing footage from surveillance cameras in the area.

About 50 people gathered at the intersection hours after the shootings for a vigil. They chanted “somebody knows who killed that baby,” ‘’turn them in” and “it ain’t snitching.” The children’s mother, Lashae Jones, carried a small stuffed animal. The crowed pressed closer to her as ministers called for prayer and peace, quoted Bible verses and sang gospel songs as they held each other.

The Rev. Danny Givens Jr., who is a cousin to the children’s mother, spoke softly, a marked change from speeches he gave Thursday when he yelled “This is black grief!” at a rally for Philando Castile.

Police fatally shot Castile Wednesday while he sat in his car during a traffic stop in Falcon Heights. His girlfriend’s 4-year-old was in the car when the officer opened fire but wasn’t hurt. Givens said he was friends with Castile.

“I couldn’t believe that this could happen again so close to home,” Givens said as the vigil ended. “A 4-year-old was in the car with Philando, and now this. Why are we letting our babies witness death? Why are we letting our babies die?”

Castile’s death and the death of Alton Sterling at the hands of police in Baton Rouge, Louisiana, has sparked a protest in Dallas that ended when a black Army veteran opened fire on police at the event, killing five officers.