A spate of shootings has left six people dead with a "random act of violence" on a train and another shooting by an 11-year-old boy.

In Chicagofour people have been confirmed dead after they were targeted by a shooter as they slept on the city's mass transit L-train system.

And in Louisiana a well-respected former mayor and his daughter have died after suffering "multiple gunshot wounds" in an attack by a child police said.

Joe Cornelius Snr, 82, and his daughter 31-year-old Keisha Miles were found inside a home around 6.30am (11.30am GMT) on Sunday, Louisiana Police Chief Jared McIver said "the city is in shock".

In Chicago Rory Hoskins, the mayor of the Forest Park area of the city where the four people were killed on a train around 5.30am (10.30am GMT) on Monday, said the victims likely didn't even see the shooter. He added: “They were shot execution-style as they slept."

Margaret Miller, 64, and three men including Simeon Bihesi, 28, and Adrian Collins, 60, were fatally shot, according to the Cook County medical examiner's office.

All of their addresses were listed as unknown. Police said they were still working to notify relatives of the fourth person killed, so his name has not yet been released.

The suspect Rhanni S. Davis, 30, was later arrested on another Chicago Transit Authority L line, according to police. Authorities charged Davis with four counts of first-degree murder on Tuesday. He is due to appear in court today (Weds).

Louisiana Police Chief Jared McIver said a 911 caller told police on Sunday morning that there were two dead people in a house in the northern city of Minden.

Responding officers found the bodies of Joe Cornelius Sr. and his daughter Keisha Miles, 31, at the residence. The 11-year-old was on the scene at the time, he said.

Chief McIver said eventually the child confessed to the killings while being questioned with an adult relative present. But he said police are still uncertain about his motives.

He added: “The juvenile gave us a story at first that just didn’t add up. Who knows why someone would do something this malicious? And at that age."

McIver declined to identify the boy by name or detail his relationship to the victims, citing Louisiana law regarding juvenile suspects.