AP News In Brief At 5:58 P.m. EDT

Authorities, too, pushed back with ominous measures apparently seeking to undercut liberal voices: jamming text messages, blocking pro-Mousavi Web sites and Facebook and cutting off mobile phones in Tehran.

The extent of possible casualties and detentions was not immediately clear. Police stormed the headquarters of Iran's largest reformist party, the Islamic Iran Participation Front, and arrested several top reformist leaders, said political activists close to the party.The activists spoke on condition of anonymity because of the sensitivity of the situation.

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Clinton rejects victory claim by Iran's Ahmadinejad, wants to know Iranians' choice

NIAGARA FALLS, Ontario (AP) — The U.S. on Saturday refused to accept hard-line President Mahmoud Ahmadinejad's claim of a landslide re-election victory in Iran and said it was looking into allegations of election fraud.

"We are monitoring the situation as it unfolds in Iran, but we, like the rest of the world, are waiting and watching to see what the Iranian people decide," U.S. Secretary of State Hillary Rodham Clinton said at a news conference with Canada's foreign affairs minister, Lawrence Cannon.