Metro Manila (CNN Philippines) — Twin explosions rocked a town fiesta in Hilongos, Leyte Wednesday evening, leaving at least 35 people injured.

Hilongos Mayor Alberto Villahermosa said a cellphone-triggered improvised explosive device (IED) went off around 9:30 p.m. while a crowd was gathered watching a boxing event at Rizal Plaza in Hilongos. A weaker second explosion followed the first blast.

Villahermosa told CNN Philippines at least 35 residents have been injured.

Most of the victims were hit below their knees, including a pregnant woman who was hit in the leg. Five other individuals are seriously wounded.

Villahermosa said those wounded were taken to the local hospital and other hospitals in Southern Leyte. He said most suffered minor injuries.

The victims were brought to the town hospital.

One of the IEDs was left near a water pump at the Rizal Plaza, where the boxing match was being held.

An earlier report from the military stated there was one cellphone-detonated IED that exploded during the boxing match but in an interview with CNN Philippines, Villahermosa said there were two explosions that night. He said the second blast came out weaker because the other IED wasn't assembled properly.

"There were two blasts. After the first blast comes the second blast," he said.

"Luckily, yung second blast di perfectly ano... sabi ng bomb expert na kulang raw yung detonating cord nila... Hindi successful yung paggawa. Parang ano lang, mahina yung pagputok," Villahermosa added.

[Translation: Luckily, the second blast wasn't perfect... The bomb expert said the detonating cord wasn't long enough. It wasn't made properly. The explosion wasn't very strong.]

Authorities said if the second blast had exploded at full force, more people would have been injured as it was made of 81 mm mortar.

No motive for the bombing has been established yet.

Villahermosa said the blast came as a surprise, since Hilongos was a quiet town and had no records of bombings or bomb threats.

"That was the first time na nangyari yun dito sa bayan na to [This is the first time that has happened in this town], " Villahermosa said.

However, in a separate interview, the mayor mentioned the Hilongos police was part of the local government's intensified campaign against criminality. He said this had resulted in the arrest of several individuals involved in carnapping, illegal drugs and counterfeit money.

A text message from the office of Leyte Governor Dominic Petilla said bomb squads and anti-terrorism units had been deployed to the crime scene.

For now, Villahermosa said the town will step up safety precautions this coming New Year.

"Siguro we will avoid all firecrackers na. And this town has, we have a festival this 31st of this month and we're expecting a big crowd again, he said.

Villahermosa said town authorities will be more vigilant in case the bombers are planning a second attack.

Tacloban City-based stringer Wil Mark Amazona contributed to this report.