Chinese police have called the car crash that killed five and injured 38 in Beijing this week a planned terrorist attack. Five men have been arrested on suspicion of planning the assault, that killed two tourists and three suicide attackers.

The police said the attackers were members of a Muslim minority. The Washington Post says that they were Uighurs from the north-western Chinese region of Xinjiang, reporting that the five people arrested were identified with "typically Uighur names." The deceased driver and passengers of the car that was used in the attack — a married couple and the man's mother — were similarly named.

The car exploded beneath a portrait of Mao Zedong hung from Tiananmen Gate. Chinese police say knives, iron rods, canisters of gasoline, and a flag covered in religious slogans were discovered inside. The five men arrested for plotting the attack were detained up to ten hours after they had fled the city. The Washington Post reports the men were tracked down with the help of police in Xinjiang, and that the men had "jihadi flags and long knives" in their lodgings.

Some Uighurs say their culture and religion is repressed under the Chinese government. Extremists have been fighting against Chinese rule in Xinjiang — designated an Uighur Autonomous Region — but this attack marks their first terrorist strike outside of the north-western area.

2013 has been particularly violent for Xinjiang itself, with more than 50 people said to have been killed as the result of multiple terrorist actions. The BBC reports that Chinese police have quickly clamped down on the region's security after the attack, raising the security level to one and apparently issuing citizens with whistles to sound if they "saw anyone suspicious with a big beard or a burka."