MANILA (AP) -- Unidentified gunmen opened fire on soldiers guarding polling precincts during special elections Saturday in 13 Philippine towns after voting was postponed last week over fears of violence.

About 2,000 soldiers and 500 regional police commandos were deployed to Lanao del Sur province to secure the special elections, elections commissioner Rene Sarmiento said. He said the gunmen fired at troops in the Masiu and Pualas townships early Saturday, slightly wounding one soldier. He said the situation was "now under control."

The Commission on Elections, Comelec, declared the May 14 polls a failure in 13 of 39 municipalities in Lanao del Sur, where election inspectors refused to man their posts because of threats from rival political clans, or because of conflicts of interest, Sarmiento said. "We cannot afford another failure of elections because it will not speak well of the Comelec and of the country in general," he said by telephone from the provincial capital of Marawi city. "We will be the laughing stock of the international community."

ABS-CBN television reported fist-fights among poll watchers of rival candidates who swapped accusations of manipulating the ballot in Kapai township. The report said there also was an attempt to let a child vote, and the head of a poll watchdog group saw one voter casting ballots three times.

The 13 Lanao del Sur towns together have about 96,400 voters, enough to affect the results of the balloting for 12 nationally elected senators, he said.

The slow manual count shows eight opposition candidates, two administration backers and two independents leading.

Meanwhile, the tabulation of results from another southern province, Maguindanao, remained suspended because of opposition allegations that ballots were "manufactured" to show administration candidates winning in the Senate race. Maguindanao has more than 300,000 voters.

An exit poll showed the opposition winning a majority of the 12 Senate positions, but President Gloria Macapagal Arroyo's allies say they won in most of the 220 districts in 81 provinces represented in the House of Representatives.

In all, more than 87,000 candidates ran for about 17,000 congressional, provincial, municipal and city posts.

Allegations of electoral fraud also marred the 2004 presidential election, when votes from Maguindanao and other provinces in a Muslim autonomous region went to Arroyo.

Arroyo has denied conspiring to rig the vote, but the allegations fueled two impeachment bids against her that were blocked by her allies in the House.