A pair of explosions destroyed the ecstatic mood and the lives of three people about four hours into Tuesday’s Boston Marathon.

The two bombs are thought by security officials to be something like pressure cookers, in which nails, ball bearings, other shrapnel, and black powder were packed, awaiting the final “tick” of simple kitchen timers. The explosions were a mere ten seconds apart; the first detonated in the middle of the crowd adjacent to the finish line, while the second erupted about 50 to 100 yards down the street. The blasts injured more than 150 people as well as killing three, one of whom was an eight-year-old boy.

Officials said that no intelligence chatter from known terrorist groups that could be correlated with the explosions had been noticed before the attack. The bombs were similar to the improvised explosive devices used against US troops in the Middle East, but no evidence of a foreign perpetrator has been reported. Some believed that a Saudi exchange student could have been behind the attacks, but he has only been questioned by the police and has not been publicly regarded as a suspect.

President Obama, Massachusetts Governor Deval Patrick, and Boston Mayor Thomas Menino all expressed sympathy for the victims and hope for recovery and justice. “Boston will overcome,” said Menino. Obama authorized his administration to cooperate fully with all security organizations; the FBI is leading this investigation.

For many, the bombings bring back haunting memories of the 9/11 terror attacks, in which nearly 3,000 people were killed. For others, especially the family and friends of the three dead, the attack brings intense grief. Only through solidarity and rational decision-making can a full recovery, both physically and psychologically, be made.