David Short, 46, died from gunshot wounds and a blast injury at a house in Folkestone Road East, Clayton, Manchester on Friday.
Nine minutes later, police received reports that shots had been fired at a second property - on Luke Road, Droylsden - where detectives said there was a second grenade blast. No one was hurt.
Police have named a second man they would like to question in connection with the two attacks - 33-year-old Anthony Wilkinson from the Beswick area.
Dale Cregan, 29, was earlier identified as being wanted for questioning. He is also wanted in connection with the murder of Mark Short, David Short's son, at the Cotton Tree Pub on May 25.
Mark Short, 23, was killed and three others hurt after a masked gunman opened fire at the pub during a 60th birthday party in May.
His father had previously branded his killers as "cowards".
Assistant Chief Constable Garry Shewan said: "Over the past three days, an intensive police operation has been underway to identify those involved in these violent attacks, which have left one man dead.
"Armed officers have also been patrolling in the Clayton and Droylsden areas. Today, we have issued CCTV footage, which shows two men outside the house on Luke Road as the grenade is thrown.
"People will no doubt be concerned when they see this footage, which shows weapons normally reserved for warfare being used in a residential street in Manchester.
"The CCTV shows just what these men are capable of and whilst we do not believe these attacks were random, clearly we should be thankful that there was no-one passing by at the time they took place, as even more people could have been seriously injured or killed."
He urged people not to approach the two men, but to contact Greater Manchester Police.
Michelle Short, mother of Mark, paid tribute to her husband.
In a statement, she said: "Dave was a loving husband, a fantastic father to Stacey and Mark and an amazing granddad to Maddisson, Karson and Mark Junior, who he idolised.
"Dave's family was everything to him, he would always be there for family and friends when they needed him.
"They have taken my son Mark and now my loving husband Dave. They may have broken our hearts but they will never break our spirits."
A 37-year-old man was arrested on Saturday in Salford on suspicion of murder. He has been bailed pending further inquiries.
A second man, 25, was also arrested on Sunday night. He remains in police custody.
Greater Manchester Police said Mathew James, 32, from Clayton, was charged with one count of murder and three counts of attempted murder on Sunday night.
Two other men - Luke Livesey, 27, from Hattersley and Damien Gorman, 38, from Glossop - were charged with Mark Short's murder and three counts of attempted murder last week.
:: Anyone with other information in relation to this investigation is asked to call police at the Major Incident Team on 0161 856 3301 or 101, or Crimestoppers on 0800 555 111.