Two U.S. mosques have been attacked in separate incidents over the Christmas weekend. On Christmas Day, just after hundreds of people finished Friday prayers, a two-alarm fire erupted at the Islamic Society of Greater Houston in Texas. Authorities say it was intentionally set. Meanwhile, officials in California’s Central Valley are investigating a Molotov cocktail attack on the Tracy Islamic Center as a possible hate crime. A study earlier this month found hate crimes against Muslim Americans and U.S. mosques have tripled since the attacks in Paris and San Bernardino. The Council on American-Islamic Relations has reported more incidents targeting mosques this year than in any other year on record.