Detectives probing two murders and a shooting in a Merseyside community are keeping an "open mind" over whether they are linked.
No formal connection has been made between the fatal shooting of Michael Rainsford, a gun blast at a primary school and the stabbing of a teenager on Monday.
With just seven days separating the incidents, police remain open to the possibility there could be links between them.
The latest tragedy unfolded yesterday afternoon, when an 18-year-old man was stabbed in the chest in Vincent Road, Litherland.
He was taken to hospital. where he was pronounced dead.
Armed police were scrambled to the area and arrested a 17-year-old boy on suspicion of murder.
He remains in custody.
Forensics officers examined the scene throughout Tuesday as they hunted for clues that could lead to a breakthrough in the investigation.
No potential murder weapon has been recovered, the ECHO understands.
The stabbing came just six days after the same community was rocked by the murder of Mr Rainsford.
The 20-year-old was shot dead when a gun was fired through a window at his home on Harrington Road, close to Vincent Road.
His death sparked an outpouring of grief in the area, where floral tributes have been left in his name.
Three people have been arrested in connection with his murder - a 22-year-old man from Seaforth and 17-year-old boys from Kirkby and Netherton.
All three have since been bailed.
Between the two murders, a gun was fired at an empty primary school in Seaforth, close to the scene of both fatal attacks.
It was reported to police on Easter Sunday after staff responded to a security alert.
Armed police were called to Rimrose Hope Church of England Primary School, on Sandy Road, at around 6.30pm.
The grounds were inspected and a staff member discovered damage to a shutter that was closed over one of the doors.
Detectives are investigating whether the shooting may have been someone test-firing a gun, or whether a stray bullet struck the building after being fired at someone, or something, else. No-one has come forward for treatment to gunshot wounds that could have been connected to the blast.
Superintendent Graeme Robson today slammed those responsible for the "senseless acts of violence" that have blighted the area in recent days.
He told the ECHO: "In the last seven days we have had a young man shot last week, the damage caused to Rimrose Hope primary school - reported to us on Sunday, and then an 18-year-old man stabbed yesterday.
"All took place within a relatively small geographical area in South Sefton. We are not formally linking all three at the moment, though we are keeping an open mind."
He said full investigation teams had been assigned to each incident and house-to-house enquiries were underway following the Vincent Road attack.
A mobile police station has been set up in the area and patrols have been increased.
Seeking to reassure people living in South Sefton following the incidents, Superintendent Robson said: "Despite the restrictions we are having to live by, from a policing point-of-view we are still out across our communities doing everything we possibly can to keep people safe.
"That will continue, that will not stop. We are as determined as ever to tackle this type of criminality.
"It doesn't get any more serious than people taking the lives of someone else.
"Whatever challenges we face through this period we are going to investigate these offences as thoroughly as ever and be as relentless as ever."
*Anyone with information can contact Merseyside Police by calling 101, or via Twitter (@MerPolCC). You can also contact Crimestoppers, anonymously, on 0800 555 111
