Six people were stabbed in the annual Gay Pride parade by an ultra-Orthodox Jew on Thursday in Jerusalem.
Thousands of attendees were marching on the road, celebrating the event before a man entered the crowd with a knife, randomly stabbing people, eyewitnesses said.
Officials say the suspect, Yishai Schlissel, was sentenced to 12 years in prison for a similar attack in 2005.
He was released from prison three weeks ago, according to Israeli media sources.
"We heard people screaming, everyone ran for cover, and there were bloodied people on the ground," Shai Aviyor, a witness told Israel’s Channel 2.
The city's ambulance service announced two of the attacked people are seriously wounded.
Prime Minister Benjamin Netanyahu called the attack "a despicable hate crime," while President Reuven Rivlin stressed on the issue of “social intolerance” saying it could mean disaster for Israel.
"In the state of Israel the individual's freedom of choice is one of basic values. We must ensure that in Israel, every man and woman lives in security in any way they choose. That's how we acted in the past and how we'll continue to act. I wish the wounded a speedy recovery," Netanyahu said in a statement.
Religious Jews harshly criticise homosexuality seeing it as abomination of their beliefs and values.
Gay marriage inside Israel is not recognised by authorities.