A Chinese rocket stage that broke apart in space this week left behind more than 700 pieces of debris, putting more than 1,000 satellites and other objects in a busy region of Earth’s orbit at risk of dangerous collisions, analysts said Friday.

The Chinese state-owned company Shanghai Spacecom Satellite Technology launched 18 internet satellites into orbit on Tuesday, laying the first building block of a communications network that is intended to compete with SpaceX’s massive Starlink constellation.

The upper stage of the rocket that launched these satellites into orbit appeared to explode shortly after releasing its payload, leaving behind an ever-growing debris field that U.S. space agencies estimate to contain at least 700 pieces of debris.

US space research company LeoLabs said the number of debris pieces was likely more than 900, making the event one of the largest ever. The debris cloud, which formed at an altitude of about 800 kilometers, will last for several years, several analysts said.

It was unclear whether the latest rocket body’s disintegration was caused by a collision with another object or an explosion of unused rocket fuel on board. US Space Command had initially said the event produced 300 pieces of debris, a number that is likely to rise as the debris cloud dissipates.

More than 1,100 satellites and other objects in space could collide with the Chinese debris, Audrey Schaffer, vice president of strategy at space tracking company Slingshot Aerospace, told Reuters.

“What we are currently observing is that over 1,100 conjunctions within five kilometers are predicted over the next three days,” Schaffer said, adding that about a third of the objects at risk are active spacecraft that are likely to be able to evade.

According to Schaffer, the remaining objects are uncontrollable pieces of existing space debris that cannot avoid the new debris. This raises fears among many analysts that a cascade collision could occur.

In 2022, a Long March 6A rocket stage broke apart in space in a similar manner, leaving hundreds of pieces of debris behind. This sparked criticism of China from Western countries and advocates of sustainable space use, who said Beijing should better control the disposal of spent rocket bodies.

“Frankly, it’s disappointing that the rocket had the same problem again,” Schaffer said. “These types of events that create potentially avoidable debris should not happen again.”