Iran President Rival's Office Attacked

As Iranians flock to the polls, a campaign organizer for reformer Mir Hossein Mousavi said about a dozen President Mahmoud Ahmadinejad supporters attacked one of his campaign offices in Tehran with tear gas.

No one was injured, and police quickly dispersed the group, said Saeed Shariati, head of Mousavi's youth cyber campaign. There was not independent confirmation of the attack.

The cyber campaign ran several Web sites and Facebook pages supporting Mousavi. Authorities blocked at least three of them Friday.

Turnout was massive and could break records. Crowds formed quickly at many voting sites in areas considered both strongholds for Ahmadinejad and Mousavi, who served as prime minister in the 1980s and has become the surprise hero of a powerful youth-driven movement. At several polling stations in Tehran, mothers held their young children in their arms as they waited in long lines.

"I hope to defeat Ahmadinejad today," said Mahnaz Mottaghi, 23, after casting her ballot at a mosque in central Tehran.

Outside the same polling station, 29-year-old Abbas Rezai said he, his wife and his sister-in-law all voted for Ahmadinejad.

"We will have him as a president for another term, for sure," he said.

Voting was extended by six hours to midnight (1930 GMT, 3:30 p.m. EDT).

The fiery, monthlong campaign unleashed passions and tensions. The mass rallies, polished campaign slogans, savvy Internet outreach and televised debates more closely resembled Western elections than the scripted campaigns in most other Middle Eastern countries.

President Barack Obama said Iran's "robust debate" leading up to elections shows change is possible there, and it could boost U.S. efforts to engage Tehran's leadership.

In a sign of the bitterness from the campaign, the Interior Ministry - which oversees voting - said all rallies or political gatherings would be banned until after the announcement of results, expected Saturday.