White House Drone
A member of the Secret Service's Uniformed Division sits in his car on Pennsylvania Avenue outside the White House.BRENDAN SMIALOWSKI/AFP/Getty Images

A small aerial drone crashed on the White House grounds in Washington, the US secret service confirmed, saying the incident was being investigated.

The agency said an officer saw and heard what was described as a two-foot (half a meter) wide commercial "quad copter" flying near the Presidential complex before crashing on its southeast side, early Monday morning.

"There was an immediate alert and lockdown of the complex until the device was examined and cleared," a Secret Service spokeswoman said, Reuters reported.

"An investigation is underway to determine the origin of this commercially available device, motive, and to identify suspects".

The spokeswoman said the drone was flying at low altitude when the incident happened, at 0308am local time (0808 GMT).

Earlier, White House Press Secretary Josh Earnest said that early indications suggested the drone posed no threat to anyone.

President Obama was not at the premises as he is due to return from three-day official trip to India with the First Lady later this week.