Numerous homes and vehicles were seen submerged in the flood waters.
The boy was tied up and provided with only one meal of poor-quality food per day.
The victim was left with a plastic bag over his head for at least eight minutes, secured with duct tape.
The announcement for the party's leadership positions, including its secretary-general, will come at a later date.
"This wasn’t just a random act," the woman said.
The 53-year-old male bus driver is assisting police investigations.
Their names all include a character that sounds similar to the Chinese word for "younger brother".
The victim is currently in critical condition and is receiving treatment in the ICU.
He is thought to have resettled in Malaysia and Singapore.
He planned to kill his family, students and teachers from his primary school, then himself.