A gunman opened fire at a grade school on Friday morning, killing at least 26 people, among which were at least 20 children roughly between the ages of five and 10, according to initial reports.

The incident occurred at Sandy Hook Elementary School in Newtown, Connecticut, which lies about 65 miles (104 km) northeast of New York City.

Local officials speaking to reporters at a press conference near the school said that police had responded to an emergency call at 9:30 EST (1430 GMT). They evacuated the building upon arrival. The gunman was found dead inside the building. Police then secured the site.

A law enforcement official says the suspect in the US school shooting is 20-year-old Adam Lanza, the son of a teacher at the Connecticut school where the shootings occurred. The attacker's mother was reportedly among the dead.

No further information about the fatalities could be provided until victims' family members had been contacted, according to local policeman, Lieutenant Paul Vance. Local officials were carrying out an investigation in cooperation with the state officials in New Jersey.

Police were also investigating a secondary crime scene at a different location where a deceased adult was found.

President Obama called Connecticut Governor Dannel Malloy to express his "condolences and concern" for the victims, according to White House spokesperson Jay Carney.

Obama: "Our hearts are broken"

Several hours after the attack President Obama addressed the US in a televised press conference.

In an emotional speech, the US leader, taking long pauses between sentences, expressed his condolences to the residents of Newtown.

"There is not a parent in America who does not feel the same overwhelming grief I do," he said.

Obama said it was time to take "meaningful action."

"As a country, we have been through this too many times. Whether it’s an elementary school in Newtown, or a shopping mall in Oregon, or a temple in Wisconsin, or a movie theater in Aurora, or a street corner in Chicago - these neighborhoods are our neighborhoods, and these children are our children. And we're going to have to come together and take meaningful action to prevent more tragedies like this, regardless of the politics."

The number of school shootings has increased over the past twenty years, the vast majority of which were carried out against teenagers or college students.

Friday's shooting in Connecticut is one of the worst to occur in the United States.

The 2007 Virginia Tech mass shooting is currently the worst on record in the United States. A university student shot dead 32 people on campus before killing himself.

kms/hc (dpa, AFP, Reuter)