Republican candidate Marco Rubio’s staff have been given the "all clear" to return to their Washington DC headquarters shortly after they were evacuated due to the discovery of white powder in envelopes.
The discovery is being investigated by the fire department and the FBI is on the scene, according to ABC News.
Mr Rubio’s team was evacuated on Tuesday afternoon to the roof of the office building.
Spokesman Alex Conant told ABC News that hazmat crews are in the office.
The evacuation has taken place on the same day that five states in the US are voting for their preferred Democrat and Republican candidates.
Mr Rubio has insisted he will win the vote in key state Florida.Reuse content