Tennessee ? A day into one of the city’s biggest murder investigations in decades – two men, two women and two boys shot and stabbed – police conceded Tuesday they had virtually nothing to go on.

Investigators said they believed the attacker or attackers were not among the dead, ruling out a murder-suicide.

But detectives faced a broad window for the killings: some time between Saturday night and Monday evening, when the six bodies and three wounded children were found in a small brick home on a dead-end street in a poor neighborhood east of downtown.

Officers went door to door looking for tips that could lead to a suspect or a motive.