I live and work in Indianapolis. Nearby, at the intersection of I-69 and I-465, a tanker truck hauling propane hit a guardrail and then an overpass nearby, causing a massive explosion. People could feel the heat 2 miles away. The fireball could be seen 15+ miles away. Interstate 465 will be closed for weeks, since the tanker blew up directly under the 465 overpass, damaging the steel girders and completely blowing out one section of the concrete support.
The tanker driver was pulled out, and despite burns on his hands, is otherwise OK. His passenger was treated at the scene. The driver of the car behind the tanker received severe burns.
I've seen plenty happen, never been in a major one in ~600,000 miles.
One spectacular accident that I saw that always stands out in my mind, and from which I learned a very important lesson, was a convertible '80s Mustang on the highway on a beautiful day. The top was down, a passenger was laying across the back seat with legs hanging over the side of the car. An empty Rubbermaid trash barrel bounced/rolled across the highway and the driver swerved to avoid it. That resulted in the car getting sideways, sliding sideways down the length of the highway as it slowly got closer to the edge.
It caught a curb and flipped up into the air, going way up high as it flipped repeatedly. It knocked down a light pole -- at the top of the pole. The pole made a distinctive "clang" as it hit the ground. Bodies flew from the car.
The car landed upside-down just short of a guardrail; a few more feet and the guardrail would have been laid across the front seat like it was put there on purpose. No matter, days later I found out that the driver died and the un-belted passengers survived.
It all looked like slow motion to me, like a movie.
Then, on the same stretch of highway, I saw two more vehicles spin out avoiding other harmless debris within a month. No collisions or injuries were apparent while observing those.
Lesson learned: When I see something on the road, if I can't get around it gracefully, I'll just go right ahead and hit it head-on. That rubber trash can would have done zero damage to that car and everybody would be ok.
I drove an ambulance for 10 years, but this was the hardest. These are pictures after the truck was dragged out of the woods.
1/28/1998. Medic 8 was responding to a mutual aid call in a neighboring county. Caller was complaining of chest pains, and they did not have any available medic units nearby. It was a in the middle of a torrential downpour, and the ambulance hydroplaned off the road, flipped, and hit a tree.
Come to find out later, that the caller thought they hurt their foot, but didn't think an ambulance was going to come out in that weather unless he told the dispatcher he was having chest pains. One friend died, and another was so mentally screwed up that he was never himself again.