TAIPEI, Taiwan (AP) — Taiwan's military said it mistakenly fired a supersonic anti-ship missile Friday that hit a fishing boat, killing one and injuring three people, on the day rival China was celebrating the Communist Party's anniversary.

The 500-ton patrol boat Chinchiang was undergoing an inspection inside a military base when the Hsiung Feng III missile was fired and landed about 40 nautical miles (75 kilometers) away in waters off the islands of Penghu near Taiwan, the official Central News Agency said.

The Defense Ministry said the missile penetrated a nearby Taiwanese fishing boat, killing its captain and injuring three crew members.

A preliminary investigation showed that missile operators likely failed to follow proper procedures, CNA said.

A full investigation was under way, while the navy sent a helicopter and boats to search for the missile, the report said.

The firing coincided with Beijing's celebrations of the 95th anniversary of the founding of the ruling Communist Party. Chinese President Xi Jinping, also the party's top leader, delivered a speech Friday calling for peaceful development of relations between Beijing and Taipei.

Tensions across the strait have escalated since Tsai Ing-wen of a pro-independence party was elected president earlier this year. Tsai has refused to endorse the concept of a single Chinese nation, and Beijing cut off contact with Taiwan's liaison office when she was inaugurated in May.

Beijing sees Taiwan as a renegade province after a civil war, although the island has functioned as an independent country and does not acknowledge Beijing's claim of authority over it.