In a letter to US President Barack Obama, Israel President Reuven Rivlin said that Israel stands "shoulder to shoulder with our American brothers and sisters", after the attack on a gay nightclub in Orlando.

He called the attack, which killed 50 people and wounded dozens more, ‘’as cowardly as it is abhorrent."

He sent his condolences and said there is "no comfort for those who have had their loved ones torn away from them."

The Orlando attack by Omar Mateen, a U.S. citizen born to Afghan parents, dominated news in Israel, which has seen a wave of Palestinian attacks in recent months.

Last Wednesday, two Palestinian gunmen killed four people at a popular shopping and restaurant area in Tel Aviv.

Israeli Prime Minister Benjamin Netanyahu, also issued a statement saying, "On behalf of the people and government of Israel, I extend our deepest condolences to the American people following last night’s horrific attack on the LGBT community in Orlando."

"Israel stands shoulder to shoulder with the United States at this moment of tragic loss. We send our heartfelt sympathies to the families of the victims and wish a full and speedy recovery to the wounded," he said.

A number of solidarity events with the victims of the Orlando attacks took place around Israel on Sunday. The Tel Aviv municipality lit its southern façade overlooking Rabin Square to display the LGBT pride, American, and Israeli flags.

29-year-old Omar Mateen is alleged to have been on the FBI’s radar after his name emerged in an investigation a number of years ago. The FBI determined that the gunman had “leanings” toward Islamic fundamentalism. He was killed by a SWAT team several hours after the attack began.

US President Obama has come under fire from Republicans for not adopting the term “radical Islamic terrorism” to describe the attack.

Obama said the probe was being treated as a terror investigation and that investigators were examining materials from the internet that the shooter may have consumed.

Obama said investigators are still looking into the motivations of the shooter and considering all possibilities.