TAIPEI (Taiwan News) — Taiwan High Speed Rail experienced a communication system disruption on Tuesday morning that caused delays of up to 30 minutes for four trains and affected about 2,000 passengers, the company said.

The disruption began at 9:11 a.m. and lasted until 10:49 a.m., during which communication with trains was intermittently lost. THSR said the cause of the malfunction is still under investigation, per CNA.

The company dispatched technicians to repair the system, and normal operations gradually resumed after communication were restored after 90 minutes.

THSR apologized to passengers and said additional staff were deployed at stations to assist travelers. Notices were also posted on its website following the incident.

According to THSR policy, passengers arriving more than 30 minutes but less than 60 minutes later than scheduled are eligible for a 50% refund of the ticket price. Those delayed more than 60 minutes are entitled to a full refund.