Armed police were seen outside a residential property in Cardiff on Saturday morning.
Residents in Grangetown said more than 20 police officers were in the area of Taff Embankment on Saturday.
They also reported seeing a number of vans appear in the area, along with what they believed to be an unmarked police van.
A spokesman for South Wales Police said a warrant was carried out at an address in the area but no offences were found to have been committed and no arrests were made.
A resident in the area, who wished to remain anonymous said: "Around three armed police vans showed up and they got out and approached this house.
"We could hear them shouting 'Armed police!' before they entered the house."
They said the small residential area was essentially surrounded by police.
"It was quite concerning," they added. The police were in attendance for around an hour, the resident added.
A spokesman for South Wales Police said: "South Wales Police conducted a warrant at an address on Taff Embankment, Cardiff, shortly after 11am today (Saturday, July 4).
"Firearms officers were deployed alongside divisional teams as a precautionary measure. No offences were found to have been committed and no arrests were made."
