An assailant stabbed six people taking part in a Gay Pride march in central Jerusalem Thursday, seriously wounding two of them, Israeli police and health services said.
Police, raising an earlier casualty toll of four, said a man was arrested, without identifying him.
Public radio said the suspect was an ultra-Orthodox Israeli Jew.
The Magen David Adom, the Israeli equivalent of the Red Cross, said two of the casualties were in serious condition.
Hundreds of police are deployed to prevent violence breaking out in the highly conservative city during the annual march.
In 2015, an ultra-Orthodox Israeli Jew wounded three Gay Pride marchers in the Holy City.
The same man, released from jail three weeks ago after having served his term, could be behind Thursday's attack, public radio said, in an unconfirmed report.
In past years, ultra-Orthodox protesters have gathered in the Mea Shearim quarter to denounce what they consider the "abomination" of homosexuality.
Israel is widely seen as having liberal gay rights policies, despite the ultra-Orthodox hostility towards homosexuals, particularly men.
Israel repealed a ban on consensual same-sex sexual acts in 1988.
*This story was edited by Ahram Online.