Thousands of people attended Plunkett Park for 5.30pm on Sunday where Errigal Ciaran and Carrickmore were competing for a place in the semi-finals of the Tyrone Senior Football Championship.
Supporters from Brocagh and Clogher were also at the GAA grounds for a 4pm tie on Sunday.
However a number of supporters were left shocked when they returned to their vehicles to find them damaged.
The damage ranged from scrapes to holes punched around the door handle area.
The cars were parked along the Cavnakeeran Road area, in and around housing developments including Shanroy and Keeragh Park.
It’s understood that attempted theft is one line of inquiry.
A silver Citroen Berlingo type van was witnessed acting suspiciously in the Shanroy area.
However wanton vandalism is not being ruled out.
Pomeroy councillor Cathal Mallaghan said, “Pomeroy is always very good at hosting big GAA matches and the club will host another big tie on Saturday.
People are normally able to park their cars safely and the stewards are there to help them, but I’m very disappointed this has happened.”
Omagh St Enda’s championship semi-final clash with Trillick at 5pm on Saturday is expected to attract several thousand more supporters to Pomeroy.
Supporters from Aghyaran and Derrylaughan will also be in Plunkett Park for their 3.15pm intermediate championship semi-final on Saturday.
It’s understood that club stewards will be on a high state of vigilance during the game.
Police have also launched an investigation after four people reported damage to their vehicles.
Officers visited Pomeroy on Monday to conduct door-to-door queries.
Anyone with information is asked to contact the PSNI on 101.
Pomeroy Plunketts said information can also be passed onto any of their club officials.