CHRISTCHURCH, New Zealand (AP) – Army troops took control of the center of the New Zealand city of Christchurch on Monday, two days after a powerful 7.1-magnitude earthquake smashed buildings and homes, wrecked roads and rail lines — but caused no loss of life.

Mayor Bob Parker extended a state of emergency for another two days as troops moved to help police secure streets and badly damaged businesses in the worst-hit central area of the city. The city center remained cordoned off, with only building and business owners allowed access.

At least 500 buildings, including 90 in the downtown area, were designated as destroyed by the quake that struck at 4:35 a.m. Saturday near the South Island city of 400,000 people. Most other buildings sustained only minor damage.

The quake cut power across the region, blocked roads with debris, and disrupted gas and water supplies, but Parker said services were being restored.

Power was back to 90 percent of the city and water supply had resumed for all but 15 to 20 percent of residents, he said. Portable toilets have been provided and tanks of fresh water placed around the city for residents.

Rain was falling Monday in the nearby Southern Alps and foothills, increasing the risk of flooding. Civil defense officials warned that stop banks, or flood protectors, weakened by the quake may fail to hold rising waters. Engineers were inspecting the banks Monday.

Around 150 people have been evacuated from a trailer park near the Waimakariri River as a precaution.

High winds overnight downed trees and power lines, knocking out power and blocking roads, but officials said it was not as severe as feared and no new serious damage had affected quake-hit buildings. Panes of glass were seen falling from damaged buildings and falling debris remained a concern, said police chief Superintendent Dave Cliff.

Only two serious injuries were reported from the quake as chimneys and walls of older buildings were reduced to rubble and crumbled to the ground. Prime Minister John Key said it was a miracle no one was killed.

Part of the reason the city escaped major injuries was because the quake happened before dawn, Key said.

“If this had happened five hours earlier or five hours later (when many more people were in the city), there would have been absolute carnage in terms of human life,” he told TV One News.

Specialist engineering teams continued assessing damage to all central city buildings Monday.