WASHINGTON - US President Barack Obama on Wednesday unveiled a sweeping and expansive package of gun violence reduction proposals, a month after the Sandy Hook Elementary School mass shooting that killed 26 people including 20 schoolchildren.

"In the month since 20 precious children and six brave adults were violently taken from us at Sandy Hook Elementary, more than 900 of our fellow Americans have reportedly died at the end of a gun -- 900 in the past month," said Obama at a White House event.

He was joined by gun-control advocates and children from around the country who wrote him letters in the wake of the Sandy Hook massacre to express concerns over gun violence and school safety.

President Barack Obama signs executive orders on gun violence flanked by 8-year old letter writer Hinna Zeejah (L), 10-year old letter writer Taejah Goode (3rd L), 11-year old letter writer Julia Stokes and 8-year old letter writer Grant Fritz (R) during an event at the White House in Washington, Jan 16, 2013. Behind the children are Hinna's mother Nadia Zeejah (L) and Julia's Dad Dr. Theophil Stokes (2nd R). [Photo/Agencies]

In the presence of an applauding crowd, the president signed 23 executive actions, which enable the White House to act immediately without congressional action. The measures include helping schools to hire police officers and increasing research on gun violence.

But Obama also acknowledged that "the most important changes we can make depend on congressional action," asking Americans to urge their lawmakers to move.

"These are a few of the 23 executive actions that I'm announcing today, but as important as these steps are, they are in no way a substitute for action from members of Congress," said Obama. "To make a real and lasting difference, Congress, too, must act, and Congress must act soon."

The Obama administration's comprehensive package of proposals also include pressing Congress for relevant legislation to renew an expired military-style assault weapons ban, impose a 10-round limit on ammunition magazines and expand background checks for all gun sales.

Obama received gun violence reduction recommendations from a White House task force led by Vice President Joe Biden earlier this week.

While the school mass shooting in Newtown, Connecticut on December 14 shocked the nation and triggered fresh calls for gun control among the public, the National Rifle Association (NRA), the country's leading gun rights organization and lobby group, has refused to back some of the White House proposals.