In April of 2013 a major terrorist attack killed 3 people and injured over 250 more when two bombs exploded at which famous American event?

Answer: In April of 2013, the major terrorist attack you're referring to occurred during the Boston Marathon. On April 15, two homemade pressure cooker bombs exploded near the finish line of the marathon, causing the tragic deaths of 3 people and injuring over 250 others.

Extra: The Boston Marathon is an annual long-distance running event hosted by several cities in greater Boston in eastern Massachusetts, United States. It is traditionally held on Patriots' Day, the third Monday of April. Begun in 1897, the event is the world's oldest annual marathon, and it's one of the six World Marathon Majors. Marathons are typically 26.2 miles long, and the Boston Marathon is particularly well-known, attracting runners from all over the world.

The attack on the marathon was a significant event in American history, bringing about heightened awareness and changes in security measures at major public events. The term "terrorism" refers to the use of violence and threats to intimidate or coerce, especially for political purposes. The Boston Marathon bombing was conducted by two brothers, Tamerlan and Dzhokhar Tsarnaev, and it led to an intense manhunt that ended with Tamerlan killed and Dzhokhar captured. Dzhokhar was later found guilty of 30 charges related to the bombing and was sentenced to death, a sentence that was overturned in 2020 on appeal but could still be reinstated after further legal proceedings. The incident united the people of Boston and the international community in support of the victims and to condemn terrorism, encapsulated by the popular slogan "Boston Strong".