A series of earthquakes struck New Zealand near the city of Christchurch on Friday, causing damage and disruption in an area still recovering from a powerful quake in February.

The tremors have injured at least two people and resulted in the closure of the Christchurch airport, said Vince Cholewa, spokesman for the New Zealand Ministry of Civil Defence and Emergency Management. He added that he did not have any information about the severity of the people’s injuries at the moment.

The first quake, with an epicenter 26 kilometers (16 miles) east-northeast of Christchurch, took place just before 2 p.m. Friday (8 p.m. Thursday, EST) at a depth of 4.7 kilometers, according to the U.S. Geological Survey. A smaller, 5.3-magnitude temblor followed eight minutes later.

The emergency services began responding, offices closed and people filed out of buildings. Fallen rocks created problems for traffic.

Then, less than an hour and half after the first tremor, as the authorities tried to gauge the damage and residents tried to calm their nerves, another 5.8-magnitude quake shook the region. Its epicenter was 15 kilometers from Christchurch and was 4.9 kilometers deep, the U.S. Geological Survey said on its website.

The string of tremors rattled a city already on edge.

In February, a 6.3 magnitude earthquake hit the central business district of Christchurch, killing more than 180 people.

The city, the biggest on the South Island of New Zealand, is in the process of rebuilding the areas that the suffered the worst damage from that quake. Many buildings are still swathed in scaffolding. Some of the weakened buildings sustained further damage on Friday, Cholewa of the civil defense ministry said.

The city has resorted to using shipping containers to house retail outlets while it repairs damage to shopping districts.

Gary Moore, who works in Christchurch, said he was having Christmas drinks with his colleagues Friday when the first quake shook the room for 15 to 20 seconds.

“People are in shock, since things were just getting back to normal” from the February quake, he said by telephone. “You can never get used to such things. This really gets into your nerves.”

Moore has reason to be jumpy: After the February quake, he and about 20 other people had to be rescued from a 17-story building where they had found themselves trapped.

The tremors Friday felt small compared with what he experienced in February, he said, but his office had still been closed and the building emptied.

He added that he could hear emergency service sirens wailing.

CNN’s Jethro Mullen and Judy Kwon contributed to this report.