(CNN) After three mass shootings left at least 32 people dead in the span of a week, FBI Director Chris Wray has ordered the agency's offices across the country to conduct a new threat assessment in an effort to thwart future mass attacks, law enforcement sources told CNN.

A command group at the bureau's Washington headquarters will oversee the effort, the sources said.

The agency said it was concerned that US-based domestic violent extremists could become inspired by the attacks to "engage in similar acts of violence."

"The FBI asks the American public to report to law enforcement any suspicious activity that is observed either in person or online," the FBI said in a Sunday statement.