A precautionary lockdown of the US Capitol was lifted after about two hours on Saturday, after a man carrying a protest sign shot himself dead.

The man died after shooting himself on the west front of the Capitol building just after 1pm, Capitol police spokeswoman Kimberly Schneider said. No one else was hurt.

Capitol police chief Kim Dine said the man had a backpack and a rolling suitcase, triggering an hours-long lockdown, and a sign that said something about “social justice”.

Robert Bishop of Annapolis, Maryland said he was biking near the steps of the Capitol when the man shot himself.

Bishop did not witness it but said there were about 60 people in the area, and that some did, including a girl and her mother who immediately began crying.

Bishop said another witness told him and a police officer that the man held up a protest sign about taxation just before pulling the trigger.

No one was allowed to leave or enter the Capitol or the visitors’ centre during the lockdown on a busy day for tourists, and some streets around the area were closed.

After being allowed to leave the Capitol, Bishop said he saw authorities taking clothes out of the suitcase.

During the lockdown, about a dozen police cars, black SUVs and an ambulance congregated at the bottom of the west steps of the Capitol, which overlooks the bustling National Mall.

Police appeared to take measurements as bomb squad members searched the area. Nearer the mall, visitors gathered, trying to figure out what was going on.

The lockdown came during Washington’s annual Cherry Blossom Festival, which attracts thousands of tourists.

Congress has been on spring recess for two weeks and lawmakers are set to return to work Monday.