The youngster, who has not been named, suffered multiple fractures and injuries to her liver and spleen and was taken to an intensive care unit.
The train operator said the woman's narrow escape was "miraculous" after she came within metres of her death.
The latest discovery comes four years after a similar find in the same region of Argentina.
The collision was captured on camera by alarmed onlookers.
"China has pretty much given up nothing in this deal."
The president will hold a high-stakes meeting with Chinese leader Xi Jinping but has canceled his sit-down with Russia's Vladimir Putin.
While Trump has routinely argued that the tariffs will encourage companies to bring jobs back to the U.S., many are simply looking for cheaper alternatives in other Asian nations.
Kremlin foreign policy aide Yuri Ushakov told reporters that Putin and Trump will meet on December 1 in Argentina, disregarding the president's suggestion that the meeting may be canceled.
More than 22,000 police and security agents are set to put the city on lockdown, with 33 protests against the summit planned.
"It's all rather unseemly, an embarrassing situation," said the local health secretary.
As part of the joint Argentina-Russia operation, authorities confiscated 360 packages of cocaine hidden in the suitcases and replaced them with flour and tracking devices.
A spokesman for President Mauricio Macri has denied the report.
The new government won't appeal a court's decision to strike down a deal with Iran over investigating the 1994 bombing of a Jewish community center.
The demonstrators underscored the resistance her conservative successor will face to his plans for change.
Alberto Nisman had drafted a request that President Cristina Fernandez be arrested for conspiring to derail his probe into the deadly bombing of a Jewish center.