The gunman who opened fire at the entrance of the Holocaust Memorial Museum in Washington on Wednesday was thought to be an 89-year-old white supremacist.

Media reports identified him as James W Von Brunn, a Second World War veteran who ran an extreme antisemitic website, Holy Western Empire.

The man was reported to have entered the museum, just a mile from the White House, shortly before lunchtime and to have fired indiscriminately, injuring a security guard, before other guards shot back. The guard later died in hospital.

Police Sergeant David Schlosser said that at least two people were being treated, including a security guard and the gunman. AFP reported that a third person was also slightly injured.

The head of the museum cafeteria, speaking shortly after the shootings, said that staff had been “locked in for their safety”. The same applied to staff at the museum’s shop.

US President Barack Obama said he was “saddened by the shooting and concerned for the wounded guard”.

Reports said Von Brunn had previously served six-and-a-half years’ jail for walking into the Federal Reserve in 1981 and brandishing a sawn-off shotgun. He had said he was upset about interest rates.