Original sentence: After the Boston Marathon bombings during the 2013 Boston Marathon, which killed 3 and injured over 260 people, police installed additional security measures, including bag checks and additional barriers while maintaining a friendly, happy atmosphere for the 2014 marathon.The 2015 Boston Marathon is going to take place in Boston, Massachusetts on Monday April 20, which is Patriots Day in Massachusetts
Edited sentence: After the Boston Marathon bombings during the 2013 Boston Marathon, which killed 3 and injured over 260 people, police installed additional security measures, including bag checks and additional barriers.The 2015 Boston Marathon is going to take place in Boston on Monday, April 20, which is Patriots Day in Massachusetts