Officials from Japan’s transport ministry on Monday ordered the immediate inspections of highway tunnels across the country after concrete slabs in a tunnel west of Tokyo fell onto moving vehicles below.

Authorities will survey 49 other tunnels and passageways of similar structure following Sunday’s accident, which killed nine people and injured two, AP reports.

Highway operator Central Japan Expressway Co. was inspecting a parallel tunnel for traffic going in the opposite direction, company president and CEO Takekazu Kaneko told AP. Both sections of the thoroughfare, which links the capital Tokyo to central Japan, were closed indefinitely.

An estimated 270 concrete slabs, each weighing 1.4 metric tons, suspended from the arched roof of the 4.7-km (3-mile) long Sasago Tunnel fell over a stretch of about 110 meters, says Satoshi Noguchi, an official from the operator.

Earlier inspections of the Sasago tunnel found nothing amiss although the operator is considering the possibility that bolts holding the panels had become loose over time. The tunnel was constructed in 1977.

The incident sparked public anger over the safety of decades-old infrastructure, particularly passageways across the mountainous country, AP reports.

Chief government spokesman Osamu Fujimura during a news conference said the country’s public roads were aged and would “need a huge investment” to ensure public safety.