In twenty minutes on May 27, 1896 the universe killed 255 people in St. Louis, Missouri and East St. Louis, Illinois.

https://en.wikipedia.org/wiki/East_St._Louis,_Illinois#The_Great_Cyclone_of_1896

On May 27, 1896, a tornado struck St. Louis and East St. Louis that remains the deadliest event in the area because of the number of people it injured or killed in such a short time. In approximately twenty minutes, the 1896 St. Louis–East St. Louis tornado killed 137 people in St. Louis and 118 in East St. Louis. The tornado's destruction spanned ten miles, including into the railyards and commercial districts of East St. Louis. During the storm, 311 buildings were destroyed and 7,200 others were severely damaged.

https://en.wikipedia.org/wiki/1896_St._Louis–East_St._Louis_tornado

The 1896 St. Louis – East St. Louis tornado was a historic tornado that occurred on Wednesday, May 27, 1896, as part of a major tornado outbreak across the Central United States that day, continuing across the Eastern United States on the 28th. One of the deadliest and most destructive tornadoes in U.S. history, this large and violent tornado was the most notable of an outbreak which produced other large, long-track, violent, killer tornadoes. It caused over $10,000,000 in damage in 1896 ($4.45 billion in today's dollars). 255 people died, and over a thousand were injured. More than 5000 people were homeless and lost all of their possessions.

While a cyclone had been predicted for the later days in May, many disregarded the warning or felt that St. Louis city would not be affected. The day started quietly, with people going about their daily business. The weather in the morning did not indicate any severe threat of a tornado. The local weather bureau predicted thunderstorms, but nothing more serious. Around noon, the clouds began to appear more ominous and the barometric pressure dropped, alarming those who knew that was an indication of a tornado.

Into the afternoon, the skies started to darken, but the Weather Bureau Observatory was not overly concerned. Many residents, however, fled to their homes, anticipating severe weather. At 4:30, the temperature fell rapidly and black and greenish clouds approached the city. Near 5:00 pm, it was as dark as it would otherwise be 3 hours later in the day. As the thunderstorm approached St. Louis, the western portion of the city was particularly affected. The winds were initially around 37 miles per hour, but they quickly increased to almost 80 miles per hour.

The first significant tornado of the day formed near Bellflower, Missouri and killed a woman. Three students died and 16 were injured when the Dye School in Audrain County, Missouri was hit at around 6:15 pm. The same tornado killed one student and injured 19 others at the Bean Creek school a few minutes later. At 6:30, two supercell thunderstorms produced two tornadoes. One decimated farms in New Minden, Hoyleton, Richview, and Irvington, Illinois.

Twenty-seven more people died in the other Illinois tornadoes of this outbreak.

The tornado spawned from the other supercell became the third deadliest and the most costly tornado in United States history. It touched down in St. Louis, Missouri, then one of the largest and most influential cities in the country. At least 137 people died as the tornado traversed the core of the city leaving a 1 mile (1.6 km) wide continuous swath of destroyed homes, schools, saloons, factories, mills, churches, parks, and railroad yards. A few of the destroyed homes were swept away. Numerous trees were downed at the 36-acre (0.15 km2) Lafayette Park, and a barometer recorded a drop to 26.74 inHg (906 hPa) at this location. Uncounted others may have died on boats on the Mississippi River, which could have swept their bodies downriver.

Where the tornado crossed the Mississippi and struck the Eads Bridge, a 2 in × 10 in (51 mm × 254 mm) wooden plank was found driven through a 5⁄16 in (7.9 mm) wrought iron plate. The tornado continued into East St. Louis, Illinois, where it was smaller, but more intense. Homes and buildings along the river were completely swept away and a quarter of the buildings there were damaged or destroyed. An additional 118 people were killed, and 35 of those deaths alone occurred at the Vandalia railroad freight yards. The confirmed death toll is 255, with some estimates above 400. More than 1,000 were injured. The tornado was later rated F4 on the Fujita scale. Enough damage was done to the city that there was some question that St. Louis might not be able to host the 1896 Republican National Convention in June.

Following the cyclone's destruction, members of Light Battery "A" and the First Regiment were placed on volunteer duty. Within an hour of the tornado striking, 32 members were on duty with ambulances and hospital corps to assist in rescue operations and to help victims. The mayor asked that both commands remain on patrol duty on May 30. Members of the bicycle corps of Company "G" First Regiment assisted when railway service was inaccessible. Telephone and telegraph wires were destroyed and streets were impassable. Officers were summoned to duty by bicycle couriers, as this way the only means of communication after the city's destruction.