MANILA, Philippines?Only three days after a bomb exploded at the Office of the Ombudsman in Quezon City, a bomb threat was sent in a text message to one of its lawyers Wednesday morning, forcing top officials to send some 500 employees home by noon.

The bomb squad of the Quezon City Police District searched the five floors of the building on Agham Road but found nothing.

Written in Filipino, the text message said a bomb with C4 component was in one portion near the office of Ombudsman Merceditas Gutierrez.

It was received by lawyer Moreen Generoso of the agency's Preliminary Investigation and Adjudication Monitoring Office about 11 a.m.

Gutierrez was not in her office Wednesday.

Sought for comment, Assistant Ombudsman Mark Jalandoni said: "This will still not deter us from our work. But we will have to strengthen our security measures."

Following the text message, Deputy Ombudsman Emilio Gonzales III immediately gathered employees outside the building and informed them of the threat. Employees were sent home starting at 11:40 a.m.

But some employees chose to stay in their offices.

Lourdes, an employee of the Corruption Prevention Office, said she and her fellow employees did not panic. "We are not scared. The explosion on Sunday happened outside the building," she said.

The daily noon mass on the ground floor also continued while many employees were leaving the building. Some 30 employees attended the mass.

"In the face of fear, whom shall we call? The Lord," Fr. Jesse Santos, who officiated the mass, said in his homily. "We don't want to begin this month with fear."

Deputy Ombudsman Orlando Casimiro said this was the first time the agency received a bomb threat since it moved to its five-story building in Quezon City in 2002.

Because of the explosion on Sunday which slightly damaged some offices, Casimiro said: "We found it prudent to declare a half-day suspension. We will resume work tomorrow."

Casimiro said he would not want to speculate on what could have motivated the threat. He said Generoso, the one who got the text message from an anonymous sender, handles different cases.

"We are just doing our job. We have remedies under the law. Those behind the threat should not resort to this," Casimiro said. The Office of the Ombudsman is tasked to probe and prosecute cases against public officials.

Last Sunday, two men hurled an explosive device which detonated inside the compound. The explosion was strong enough to damage the water treatment plant, some windows of the second floor rooms, as well as the employees' shuttle service.