Two men who were in the Boston area for college Halloween parties last weekend set off fireworks in an empty Harvard Medical School building, authorities said Tuesday in announcing their arrests.

Logan David Patterson, 18, and Dominick Frank Cardoza, 20, were arrested Tuesday morning on charges of conspiracy to damage by means of fire or an explosive.

Hours after their arrest, Patterson and Cardoza were escorted into U.S. District Court in Boston in handcuffs as relatives of at least one of them looked on. Judge Jessica Hedges asked if they understand the process, and both said they did. She then ordered them released pending trial.

Neither Patterson, who is from the Boston suburb of Plymouth, nor Cardoza, who is from the Cape Cod town of Bourne, had an attorney as of early Tuesday afternoon. Cardoza also didn’t immediately respond to an Instagram message seeking comment.

AP Video shot by Rodrique Ngowi.