The Moro National Liberation Front had prepared for their attack in Zamboanga City as early as January this year, a police official said on Tuesday.

Based on their investigation on arrested and surrendered Moro gunmen, Philippine National Police deputy chief for Operations Deputy Director General Felipe Rojas Jr. said that the MNLF started to store ammunition in the city in January.

“They said that since January, they started training and storing ammunition little by little,” Rojas told reporters in a press briefing at Camp Crame.

“We know how long the the shoreline of Zamboanga is and it’s hard to detect people coming from Basilan and Jolo,” Rojas also said.

The MNLF stormed Zamboanga City on Sept. 9, in an attempt to hoist their flag in the city hall, which led to a bloody three-week standoff. They took civilians as hostages and used them as human shields.

Rojas said they were investigating who funded the attack

“We are investigating who funded this. The guns they used are already old but still fully operational,” Rojas said.

Rojas said things could have gone worse if the MNLF was able to put up their flag there.

“We recovered so many firearms. It would have been worse if they were able to reach the city hall,” Rojas said.

He also said that they were able to thwart the attack by setting up checkpoints in different parts of the city.

The PNP is now spearheading the clearing operations. It is expected to last for two weeks, and an assessment will be made if the evacuees can go back to their homes.

There were also no plans to pull out thousands of police troops there, Rojas said.

Over 200 had been killed from the fighting between the state security forces and MNLF. Five of these were policemen. At least 100,000 persons were also displaced.