Police are linking two 'targeted' firearms incidents in which handguns were fired.
Officers are appealing for witnesses following the two incidents in Billingham within a day of each other.
Two cars, one black and one white, were seen in the Low Grange area of Billingham at about 2.45pm on Tuesday.
The occupants of these vehicles are believed to be known to each other.
Whilst stationary on Windlestone Road a male has approached the black vehicle on a pedal cycle.
The male on the pedal cycle produced a handgun and fired two shots at the black car, before riding away on his bike.
A second incident occurred after shots were discharged towards an unoccupied address on Hylton Road in Billingham at about 10.40pm on Wednesday.
No one was injured in either incident.
Detectives are satisfied that these incidents are linked.
They are believed to be targeted attacks that were not random in nature.
"Detective Inspector Jon Tapper, from Cleveland Police Major Crime Team, said: “Incidents of this nature are thankfully very rare and detectives are doing everything possible to identify and trace those involved.
"These incidents are believed to be targeted.
“Yesterday evening officers attended a public meeting in the Billingham area to reassure the public that work is ongoing to bring those responsible to justice.
"There was a lot of police activity around the area yesterday evening and throughout the night and we would like to thank the public for their support in this investigation so far.
“Anyone with information is asked to contact Cleveland Police.”
This morning a 21-year- old male was arrested in connection with these incidents and he remains in police custody. Further arrests are anticipated.
Officers would appeal for any witnesses to contact Cleveland Police Major Crime Team on the non-emergency number 101 or Crimestoppers anonymously on 0800
555 111 or www.crimestoppers-uk.org