CHRISTCHURCH (BNO NEWS) — A powerful earthquake rocked New Zealand’s second largest city on early Saturday morning, seismologists said, but no major damage was immediately reported.

The 7.4-magnitude earthquake at 4.35 a.m. local time (1635 GMT Friday) was centered 30 kilometers (19 miles) northwest from Christchurch, the country’s second-largest city. It struck about 33 kilometers (20 miles) deep, making it a shallow earthquake, according to GeoNet, the country’s seismological agency.

The United States Geological Survey (USGS) estimated the strength of the earthquake at 7.0 on the Richter scale.

The USGS estimated that around 22,000 people likely perceived ‘extreme’ shaking, which could potentially result in ‘very heavy damage’. Another 187,000 people were estimated to have perceived ‘violent’ shaking, which could result in ‘heavy’ to ‘very heavy’ damage.

The agency further estimated that about 202,000 people perceived ’severe’ shaking, while 24,000 others perceived ‘very strong shaking. Thousands more felt less intense shaking.

There were no immediate reports of fatalities, but a Christchurch police spokesman said several people sustained minor injuries. “It could be a lot worse,” he said.

The police spokesman said minor to moderate damage was being reported, but said assessments were still underway. “A lot of people are calling to report damage,” another police spokesperson told BNO News.

The country’s Ministry of Civil Defence and Emergency Management said it was still assessing the situation and activated the National Crisis Management Center in response. It advised people to prepare for aftershocks.

Fairfax Media Publications-owned Stuff reported several buildings had been destroyed by the earthquake, but police said several hours after the earthquake that they had no reports of collapsed buildings. “Oh my God. There is a row of shops completely demolished right in front of me,” a resident told Stuff.

A person who answered the phone at Christchurch International Airport told BNO News he felt ‘major shaking’ that was followed by several aftershocks. He said people were evacuated from the airport terminals, but were starting to re-enter the terminals about an hour later. He said there was no major damage at the airport.

Soon after the earthquake, at 4.53 a.m. local time (1653 GMT Friday), a moderate 5.7-magnitude earthquake struck about 50 kilometers (30 miles) west-northwest of Christchurch. It struck about 17.4 kilometers (10.8 miles) deep, according to the USGS.

No tsunami warning was issued after the powerful earthquake, which could be felt throughout the South Island. “No destructive widespread tsunami threat exists based on historical earthquake and tsunami data,” the Pacific Tsunami Warning Center said in a bulletin.