Simplify the following text for a Grade 7 native English-speaking person.
Original: The 7 July 2005 London bombings ( referred to often as 7\/7 ) were a series of coordinated suicide attacks upon Londoners using the public transport system during the morning `` rush hour '' .
Simplified: The 7 July 2005 London bombings were a series of coordinated suicide bomb attacks . They were aimed at London 's public transport system during the morning rush hour .