Armed woman arrested while demonstrating outside White House during immigration speech
Orange lights to celebrate Halloween illiminate the White House in Washington (AFP)

A woman demonstrating outside the White House on Thursday night was arrested for carrying a gun, the Secret Service said, shortly after President Barack Obama began a speech unveiling sweeping reforms to the U.S. immigration system.

April Lenhart, 23, of Mount Morris, Michigan, was arrested around 8:30 p.m. local time, Secret Service spokesman Robert Hoback said in an email.

Obama had started his speech some 30 minutes earlier, during which he imposed the most sweeping immigration reform in a generation.

The executive actions ease the threat of deportation for some 4.7 million undocumented immigrants and set up a clash with Republicans who vow to fight his moves.

Hoback said Lenhart was demonstrating along the north fence of the White House complex when authorities saw a holstered handgun on her hip.

She was charged with possession of an unregistered firearm and ammunition, and carrying a pistol without a license. Hoback said she refused to make statements to authorities.

(Reporting by Curtis Skinner in San Francisco; Editing by Paul Tait)