A teenager was shot in an attack on a property in Huyton.
Emergency services were called to Wimborne Close shortly before 9pm following reports that five gunshots had been heard in the local area.
Damage consistent with a firearm discharge was found to a house while a teenager was found in a nearby property with a bullet wound to the torso.
Less than an hour earlier, police had arrested a 51-year-old man from Runcorn in connection with a suspected arson in nearby Kingsway.
He was also arrested for an intent to endanger life and also on suspicion of assault and was taken to a local police station for questioning.
Detectives do not believe that the two incidents are connected.
Anyone with information on either incident is asked to contact @MerPolCC, call 101 or provide information to Crimestoppers anonymously on 0800 555 111.