TOULOUSE, France — A 23-year-old Frenchman of Algerian descent claimed responsibility on Wednesday for the methodical killings of four men and three children in this region over the past 10 days, officials said, after barricading himself in a small apartment building in Toulouse surrounded by hundreds of police officers.

The suspect was identified as Mohammed Merah, 23, a former garage mechanic who had made trips to Afghanistan and Pakistan, and said that he had been trained by Al Qaeda. Mr. Merah remained retrenched in an apartment building in the quiet neighborhood of Côte Pavée into the early hours of Thursday morning, in a standoff that had gone on for nearly a day. Several explosions and gunshots could be heard just before 2 a.m. Thursday, a few hours after three blasts rattled the area in what French news media reported was an attempt to destroy a window at the suspect’s apartment, as the police tried to let in the night cold in the hope that Mr. Merah might surrender peacefully.

French officials have indicated that the police will make every effort to take him alive.

In the first six hours of the standoff, which began before dawn on Wednesday, the suspect fired several heavy volleys at officers trying to enter his apartment, wounding two, though neither seriously. At one point he tossed a .45-caliber pistol from the window, the same kind used in each of the three attacks, and was given some kind of “means of communication,” according to the authorities, presumably a cellphone or walkie-talkie.

“He expressed no regrets, saving only that he did not have the time to reach more victims,” François Molins, the Paris prosecutor responsible for overseeing antiterror investigations in France, said, adding that Mr. Merah said he had planned to kill a soldier on Wednesday morning, and at some point to kill two police officers here.