Which city's subway system was paralyzed by a deadly nerve gas attack in 1995?

On 20th March 1995 at the height of the morning rush hour in Tokyo, Japan, five two-man terrorist teams from the Aum Shinrikyo religious cult, riding on separate subway trains, converge at the Kasumigaseki station and secretly release lethal sarin gas into the air. The terrorists then took a sarin antidote and escaped while the commuters, blinded and gasping for air, rushed to the exits. Thirteen people died and over 5,500 were treated in hospitals, some in a comatose state. Most of the survivors recovered, but some victims suffered permanent damage to their eyes, lungs, and digestive systems.

A United States Senate subcommittee later estimated that if the sarin gas had been disseminated more effectively at Kasumigaseki station, a hub of the Tokyo subway system, tens of thousands might have been killed.