Authorities of the South Luzon Expressway (SLEX) immediately summoned chemical and LPG experts to avert an explosion from the leaking tanker.
Northbound and southbound traffic had to be rerouted away from the accident site in Barangay Sto. Tomas for fear that the tanker might explode.
Traffic along the expressway remained heavy as of press time.
"For the safety of motorists, we were forced to reroute the northbound traffic via the Sta. Rosa exit and the southbound traffic via the Carmona exit before noon yesterday," Onie Salvanera, SLEX chief patroller, said.
Salvanera said Rosita Orense, 52, died on the spot when the LPG tanker fell on their shanty below the Calabuso Bridge in Barangay Sto. Tomas.
Those injured were identified as Ely Bantayan, 33; Boy Manceras, 40, and his mother Virginia, 63; spouses Perfecto, 45, and Marilyn Escubido, 26, and their four-year-old son Joshua. They were reported to be in critical condition at the Perpetual Hospital in Biñan.
Authorities said the LPG tanker fell off the bridge after a van smashed into its rear. Tanker driver Daniel Terminez lost control of the wheel, causing the tanker to plunge into the shanties.
The van driver escaped with the vehicle toward Manila after the incident.