Saudi Ambassador to U.S., Adel bin Ahmed Al-Jubeir: "What occurred today in Boston is a heinous crime which contradicts the values of humanity."

According to a press release, Ambassador Al-Jubeir "strongly condemned" the bombings and offered condolences to the victims' families. He also expressed "confidence" that the perpetrators would be brought to justice.

Mayor of London Boris Johnson: "The bombings in Boston are shocking, cowardly and horrific, and the thoughts of all Londoners this morning will be with the victims. Boston is a proud City built on history, tradition and a real sense of community. These attacks were aimed at its core, at innocent men, women and children enjoying a Spring day out at a major sporting event. We do have robust security measures in place for Sunday's London Marathon, but given events in Boston it's only prudent for the police and the organisers of Sunday's race to re-examine those security arrangements."

Russian President Vladimir Putin offered his country's assistance in investigating the bombings. Putin said in a condolences note published on the Kremlin's website Tuesday that the international community should come together to fight terrorism.

French President Francois Hollande: sent his condolences to the families of the victims and expressed "France's total solidarity" with the American people and authorities.

Foreign minister Laurent Fabius issued a statement saying "our thoughts are with the families of the victims and with the injured". He also offered support and solidarity to the local and federal authorities. He added that the French consulate in Boston was mobilized to help any French citizens involved. A total of 158 French nationals had signed up for the marathon.

Muslim Brotherhood of Egypt: The Freedom and Justice Party (FJP) said that it " categorically rejects as intolerable the bombings committed in the U.S. city of Boston. The FJP offers heartfelt sympathies and solemn condolences to the American people and the families of the victims and wishes a speedy recovery to the injured.

Islamic Sharia (law), accepted by the FJP as a framework of reference, strongly condemns attacks on civilians and terrorizing innocent people, regardless of their religion, race, color or sex.

The heinous attacks in Boston today highlight the need for the international community to unite in order to achieve justice and a decent life for all peoples and communities to ensure non-recurrence of such violent and tragic crimes."

Australian Prime Minister Julia Gillard: "Australia unreservedly condemns this brutal and senseless attack on what is a great event known around the world - one people participate in to have fun as their families and friends watch on.

"The images we've seen have been truly shocking ones and our thoughts today are with those who have lost loved ones and our condolences go to those who have lost family and friends in this tragic event... Our thoughts, our condolences are with those in Boston and we will continue to provide advice as we can about who is responsible for this senseless and very, very, cruel attack."

Rio Olympics organizers: Rio Olympic organizers expressed their sadness after the deadly explosions at the Boston Marathon on Monday and quickly moved to reiterate that security is "a top priority" as the city prepares for the 2016 Games.

The 2016 Olympic committee offered condolences to those affected by the explosions and said it is constantly working with the local government to guarantee the games' safety.

"Rio 2016 offers its deep thoughts and condolences to everyone affected by this tragic incident," the committee said in a statement.

"This is a horrible crime, and we call on all of us as Americans to work together to bring those responsible to justice," it said.

To attack people on what is supposed to be a day of jubilation is criminal and inexcusable, the council said.

"This is a time for us to show resilience and calmness, as we come together to help the American public recover from this heinous act," said Salam Al-Marayati, MPAC president.

The Council on American-Islamic Relations (CAIR), a Muslim civil rights and advocacy organization, also condemned the bomb attacks.

"American Muslims, like Americans of all backgrounds, condemn in the strongest possible terms today's cowardly bomb attack on participants and spectators of the Boston Marathon," said its national executive director Nihad Awad.

"We urge people of all faiths to pray for the victims and their loved ones and for the speedy recovery of those injured. We also call for the swift apprehension and punishment of the perpetrators," he said.