Italian police detained two more suspects in a bomb attack on a Milan army barracks and found a large quantity of bomb-making chemicals during overnight searches, anti-terrorism prosecutors said Tuesday.

The operation followed Monday's attack at the main gate of the Santa Barbara army barracks by a 35-year-old Libyan man, who was seriously wounded in the blast. The motive is not known.

The explosion caused little damage to the barracks, and slightly wounded the guard who stopped the attacker.

Anti-terrorism prosecutor Armando Spataro told The Associated Press that another Libyan and an Egyptian have been detained overnight as suspected accomplices in the bombing. Spataro later told a news conference that authorities had found 88 pounds of ammonium nitrate and other bomb-making substances.

Ammonium nitrate, an easily obtainable fertilizer ingredient often sold in 110-pound sacks, had been purchased about a week ago by the Libyan man who carried out the attack, prosecutors said.

Prosecutor Maurizio Romanelli, who is heading the investigation, told the AP it was not immediately clear if the three suspects were part of a wider terrorist network or if they had plans for further attacks.

"We still need to look more deeply," Romanelli said.

The investigating judge will decide whether to formally charge the latest two suspects. The Libyan man arrested Monday following the explosion is being held initially on a charge of building an explosive weapon, Spataro said.

The attacker, identified as Mohamed Game, has been in Italy since 2003, and has two children with an Italian woman with whom he has been living in Milan, Spataro said. "It seems he had financial troubles and was unemployed," he said.

Italian news reports said Interior Minister Roberto Maroni was meeting later Tuesday with top intelligence and security officials about the bombing investigation.

"It is a serious and worrying act that should neither be underestimated nor exaggerated," Alfredo Mantovano, a deputy in the interior ministry, was quoted as saying by the Apcom news agency.