The unrest broke out over student anger against new quotas for government jobs, including 30% for the families of those who fought for independence from Pakistan.
Thick black smoke was seen billowing from one tanker and crew were rescued from life rafts and flown to hospital. Environmental authorities are preparing for potential oil spills.
The 1994 blast, which killed 85 people, was Argentina's deadliest terrorist attack, but there's a "deafening silence" around the push for answers, journalist Javier Sinay says.