WASHINGTON - Police in the US city of Boston announced on Wednesday that three additional suspects were taken into custody for the April 15 Boston Marathon bombing, which killed three people and injured about 200 others.

"Three additional suspects have been taken into custody in connection to the attack on the Boston Marathon," announced the Boston Police Department in a statement.

The police provided no further details, but stressed that " there is no threat to the public safety."

The Boston Globe newspaper reported on Wednesday that the three suspects were all college students connected to Dzhokhar Tsarnaev, the 19-year-old suspect who has been apprehended and charged for the Boston bombing.

The three allegedly helped Dzhokhar Tsarnaev after the bombing, said the report.

CBS News also reported that the three were accused of harboring and aiding the bombing suspects after the attack.

Twin blasts occurred on April 15 near the finish line of the Boston Marathon, causing heavy casualties. The FBI identified two brothers, Dzhokhar and 26-year-old Tamerlan Tsarnaev, as suspects in the case. Tamerlan died after a shootout with the police on April 19, while Dzhokhar was charged last week with using a weapon of mass destruction against persons and property.

At a White House news conference on Tuesday, US President Barack Obama said that one of the dangers the country now faces comes from "self-radicalized individuals who are already here in the United States -- in some cases may not be part of any kind of network, but because of whatever warped, twisted ideas they may have, may decide to carry out an attack."