An investigation began yesterday after officers were called to reports of a disturbance on Leonard Street in Hull at around 3pm.
The 35-year-old man was found with serious injuries and taken to Hull Royal Infirmary, where he died at 9pm.
Humberside Police said today that the man had been formally identified, but did not release his name.
One man has been arrested in connection with the incident and officers are searching for others identified as suspects.
Detective Chief Inspector Alan Curtis said they were working closely with the community and had stepped up patrols to offer reassurance.
“Extra police are being deployed in the area to support communities, especially those in the close proximity to the incident," he said.
"I would like to assure members of the community that we believe this incident to have been a targeted attack.
"There is a strong neighbourly spirit in the area and I would encourage the very vigilant local community to work with us to establish the circumstances of this incident and locate the outstanding suspects.”
Officers are particularly interested in talking to anyone who was in the Leonard Street or Browning Close area between 2.30pm and 3.30pm yesterday.
Phone the non-emergency number 101, quoting log 304 of 26/07/2017.