(JTA) — A Jewish-Israeli teenager is in police custody for allegedly planning an attack on left-wing demonstrators at a Tel Aviv march.

The 18-year-old man was arrested at the Dec. 19 rally after throwing a glass bottle at protesters, according to the Times of Israel. No one was injured, and the arrest was not reported in the media until Monday.

Some 3,000 people attended the rally protesting right-wing incitement against left-wing advocacy organizations.

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The teen, who was carrying several bottles and a large kitchen knife, told police he had planned to attack the demonstrators, the Times of Israel reported, citing Channel 10 news.