Rescuers broadened their search of collapsed buildings in New Zealand's quake-shattered city of Christchurch on Thursday, as hopes faded of finding any more survivors in the hardest-hit office blocks downtown.

Police said Thursday that up to 120 bodies may still lie trapped in the tangled concrete and steel that was the Canterbury Television building, where dozens of students from Japan, Thailand and other Asian countries were believed buried when an English-language school collapsed along with other offices.

The official death toll from Tuesday's 6.3-magnitude temblor stood at 76, based on the number of bodies that have been recovered from throughout the city and brought to a special morgue. The missing were listed at 238 — though officials stressed that many of those may be safe but not yet accounted for.

"We know there are more bodies yet to be recovered and we are in the process of doing that," police Superintendent Dave Cliff told a news conference Thursday.

Prime Minister John Key declared the quake a national disaster and analysts estimate its cost at up to $12 billion.

The damaged buildings in and around Christchurch numbered in the thousands, including many of the older structures in Lyttelton, a port town just southeast of the city and closer to the quake's epicenter. Residents there wandered through the dusty, brick and glass-covered streets, pausing to offer each other hugs and ask the ubiquitous question: "How's your house?"

"It was just horrific," 63-year-old teacher's assistant Kevin Fitzgerald said of Tuesday's quake. "I thought the devil was coming up out of the earth."

The popular Ground deli and cafe was in ruins, hugs slabs of its walls lying on the sidewalk in a jumbled pile. Glass shopfront windows had been blown out

In Christchurch, hundreds of foreign specialists — from the U.S., Britain, Japan, Singapore and Taiwan — arrived to bolster local police and soldiers and allow teams to fan out further afield to smaller buildings not yet checked.

"Now we've got the capability of going out and doing searches in areas where there may still be people trapped that hitherto we haven't been able to address," Civil Defense Minister John Carters said.

Christchurch police superintendent Russell Gibson said that the last survivor had been pulled out at 2 p.m. Wednesday, and no one had been found trapped in the rubble since. Gibson said the operation had become one of body recovery, though he rejected suggestions that rescuers were abandoning hope of finding anyone alive.

The rescue effort had been concentrating on the Canterbury Television, or CTV, building, and one other downtown block that crumbled to the ground when the temblor struck shortly before 1 p.m., at the height of a busy Tuesday.

Police said Wednesday they had given up hope of finding more survivors at the CTV building and work there shifted from rescue to recovery. Teams pulled four mangled bodies from the rubble overnight, Cliff said Thursday.

He said that "between the late 60s and 120 bodies, at the upper limit," were still in the building.

The King's Education language school, in the CTV building, released a list Thursday on its web site of 141 students and teachers associated with the facility, with at least 37 mostly Asian students missing and presumed in the building.

At least 10 other Asian students were injured and hospitalized, two of them severely injured. The status of an additional 44 teachers and students was unclear.

The Japanese government said 27 Japanese were missing in the quake zone.

JP Morgan analyst Michael Huttner conservatively estimated the insurance losses from the quake at $12 billion. That would be the most from a natural disaster since Hurricane Ike hit Texas and Louisiana in 2008, costing insurers $19 billion, according to the Insurance Information Institute.

Key said the New Zealand economy could withstand the impact of the quake, the second to strike Christchurch since September.

"Christchurch's economic activity will be much less for a while," he said. "The government will be doing everything it can to economically get Christchurch back on its feet."

Tuesday's quake was less powerful than the 7.1 temblor that struck before dawn on Sept. 4 that damaged buildings but killed no one. Experts said Tuesday's quake was deadlier because it was closer to the city and because more people were about.

Officials told people to avoid showering or even flushing toilets, saying the damaged sewer system was at risk of failing. School classes in the city were suspended, and residents advised to stay home.

Tanker trucks were stationed at 14 spots throughout the city where residents could come to fill buckets and bottles, civil defense officials said, and people asked to catch and save rainwater.