A magnitude 6.1 earthquake shook southern Mexico early Thursday and was felt strongly in this capital, although there were no immediate reports of casualties or serious damage, officials said.

The epicenter of the temblor, which struck at 3:20 a.m., was located in a sparsely populated, mountainous area southeast of the town of Ciudad Altamirano, Guerrero state, the National Seismological Service, or SSN, said.

Twenty minutes after the initial temblor, which occurred at a depth of 40 kilometers (25 miles), the SSN detected a magnitude 4.1 aftershock.

The earthquake did not cause serious damage in Mexico City or cause any disruptions, Mayor Marcelo Ebrard said in a statement following an inspection of buildings and strategic areas of the capital.

Operations were briefly halted at Mexico City's international airport but were resumed after an inspection of the runways, Ebrard said.

Guerrero Gov. Angel Rivero also said on Twitter that he had received no reports of serious damage and that hospitals were operating normally.

The epicenter was located near Mexico state, but its governor, Eruviel Avila, also said there were no reports of victims or material damage.

Wednesday's temblor comes eight days after a magnitude 7.2 earthquake struck northern Guatemala and was felt strongly in the Mexican state of Chiapas.

That Nov. 7 quake killed 52 and injured 200 in Guatemala, but left no victims and caused only slight material damage to some buildings in Mexico.

Mexico's SSN has since detected 417 aftershocks with magnitudes ranging from 3.7 to 6.2. EFE