A number of shots were fired at a Sinn Féin office in west Belfast last week, police have said.
Detectives believe it happened in Monagh Crescent in Turf Lodge on Thursday 3 January at about 02:20 GMT.
On Tuesday, the Police Service of Northern Ireland (PSNI) received reports that a bullet casing had been found outside the premises.
A report was made on Thursday that a masked man had fired shots at the office.
Sinn Féin MLA Pat Sheehan said the party would not be "intimidated or deterred" from serving "all the people of these communities".
"Sinn Féin contacted the PSNI on Tuesday and reported the discovery of the casings," said Mr Sheehan.
"People then told us yesterday that they had heard what sounded like shots being fired last week.
"We checked the CCTV footage at the office and confirmed to police that shots had indeed been fired."
Mr Sheehan said it was the second attack on the office in three months.
"There was a previous attack on 7 October and only weeks later I was told by police of a threat to my life," he added.
The PSNI's Det Sgt Sam McCallum described this month's attack as a "reckless attack in what is a built-up residential area".
"Someone could easily have been injured or worse by a stray bullet," he added.
Police have appealed for anyone with more information to come forward.