PG-13 violence type: blood and gore.
Nightcrawler is seen breaking into the home of the president of the USA, he knocks over and pushes guards out the way while they shoot at him, he then tries to stab the president but fails. It's not implied that anyone dies and no blood is seen.
Magneto is hit over the head by a man with a baton.
A man dies after the iron in his body is sucked out by Magneto. Magneto then gathers the iron particles into small balls and uses them with power as projectile weapons to smash open his prison and kill the guards before escaping. This scene contains a very small amount of blood.
Many mutants are shot by tranquilizers, most of them are students. Roaring with full battle fury, Wolverine uses his claws to kill lots of soldiers, it is all quickly edited and from a particular angle so that no blood or gore is seen. One mutant is who is shot at uses his power to become a super strong being of metal in time to defend himself. Some people are also thrown about etc.
Wolverine is shot in the head by a police officer, a single drop of blood drips out of the wound.
Pyro flips out and throws fireballs at police cars, causing them to explode. Nobody seems to die, but police officers are seen covered ashes and with burned clothing.
In a flashback, Wolverine is seen covered in blood.