Grey wolves have made a comeback since hunting was banned
Swedish hunters have begun culling wolves for the first time in 45 years after parliament ruled that numbers needed to be reduced again.
More than half the quota of 27 may have died on the first day alone with nine shot dead in Dalarna and up to nine killed in Varmland, Swedish radio says.
Hunters have until 15 February to complete the cull, which will leave Sweden with an estimated 210 wolves.
Some 10,000 hunters were reported to be planning to take part in the hunt.
Hunting in the county of Dalarna was halted as the county's individual quota was nine wolves.
Varmland's quota of nine "may also have been filled", the radio reported later on Saturday.
In Dalarna, hunters reportedly injured another five wolves.
Every time a hunter shoots and hits a wolf he has to report it to the county authorities, so they can keep track of the local cull.
Earlier, hunters insisted there were measures in place to prevent them shooting too many.
"There's a lot of regulation, hunters have to check the quota every hour," Gunnar Gloersson, of the Swedish Hunters Association, told Swedish radio.
Nevertheless, the Swedish Society for Nature Conservation was critical of the decision to proceed with the cull, saying it was against EU legislation as the Swedish wolf population had not reached a healthy level.
A formal complaint was to be issued to the EU Commission, Swedish radio said.
The hunt is timed to end before the mating season, which begins in mid-February.
Wolves were hunted to near extinction in southern Scandinavia until a hunting ban was imposed in the 1970s.
Sweden and Norway have worked together to reintroduce the species to the forests along their border. When Norway culled some wolves in 2001, saying the population had spread too far, Sweden lodged a protest.
But the Swedish parliament recently decided there should be at most 210 wolves in Sweden.
Michael Schneider of the Swedish Environmental Protection Agency says that was the level last year, and since then more than 20 pairs of wolves have had pups.
"We have to remove this increase to keep the population at this level," he said.
Mr Gloersson, of the hunting association, said: "We have a lot of problems with wolves - in reindeer areas, with livestock, and for hunters they kill our valuable dogs."
"Since they came back we have to live with them, but we have to keep their numbers down."
He said the success of the cull would depend on the weather.
"The only easy way to hunt wolves is if we have snow, so the hunters can track them on the snow. If we don't have snow I don't think we'll even be able to reach the quota of 27 wolves," he said.