TIGARD, Ore. -- Authorities are investigating reports of Nazi flags being placed around the Tigard area.

Tigard police said they received three calls over the last three days from people who spotted the swastika symbol.

Police took a complaint Tuesday of one of the flags flying on Highway 217 just south of 72nd Avenue. Another report came in Thursday morning of a flag near Highway 217 and I-5.

And a third report was made Thursday night when a flag was spotted on top of a Plaid Pantry store on Highway 99W. Crews responded to the store and took down the racist symbol.

The flags were usually hung up with red balloons, allowing the flags to flap in the wind.

In addition to the three Tigard reports, a woman said she saw the swastika symbol near Interstate 5 in Tualatin earlier this week. She said it was displayed close to the freeway, near the Claim Jumper restaurant.

Police said the person responsible for placing the flags could face charges of criminal mischief. As of Friday, there were no suspects in the case.

Tigard police have reported the incidents to the state biased crimes unit.