The Palmdale office of former Rep. Katie Hill, D-Agua Dulce, was evacuated Monday afternoon after a suspicious envelope was delivered to the two-story building.

First responders arrived at the 1000 block of West Avenue M 14 at around 12:03 p.m. for “a hazmat incident at a congressional office,” said Cheryl Sims, a supervisor with the Los Angeles County Fire Department.

The Los Angeles County Sheriff’s Department said it was unclear whether the suspicious envelope was sent directly to Hill, and it contained an unknown white powder that affected at least two people in the building.

“We had two patients affected and two ambulances were called but not sure if they were transported or not,” said Sims.

The building was evacuated as a result of the incident.

Deputies with the Palmdale Sheriff’s Station responded and concluded their investigation around 3:30 p.m. From there, the FBI took over the case, said sheriff’s Lt. Joshua Bardon.

Officials with the FBI were unavailable for comment on the investigation Monday.

“There was a suspicious package that arrived to the 25th Congressional District’s office in Palmdale,” said Kassie King, spokeswoman for Hill. “Authorities took all precautions necessary and after a thorough vetting of the office and package we have now been given the all-clear.”