Wylie police said vandals wrote racially and sexually charged graffiti on several properties south of State Highway 78 and Kirby Road.
Police said homes, businesses, sidewalks and cars have been spray-painted with ethnic slurs, sexual images and threats seven times this week.
"We want to stop this before it gets more out of hand than it already is," Detective Venece Perepiczka said.
Rochelle Ritzi said she noticed graffiti on her garage door when she was leaving her home with her daughter.
"I was just in disbelief, almost thinking, 'Is this real?'" Ritzi said.
A swastika and the words "Your (sic) next" were painted on the door.
"I was scared that someone was in our house," Ritzi's daughter said.
Ritzi said the graffiti prompted a difficult conversation with her daughter.
"There was another house that was hit on the other side of the street with the N-word, and she had no idea even what that meant, so we had the conversation about what that meant and the history behind it," she said.
Willie Jones said he believes a message sprayed on his neighbor's garage door was intended for him.
"I just feel like they're trying to get the message over to me, but they don't have to go through all that to get the message to me," he said.
Investigators said each act is connected but stopped short of saying people were targeted.
The Wylie Police Department is adding foot patrols in some neighborhoods.