NINE PEOPLE ENJOYING Fourth of July festivities in the United States’ capital were shot and hurt, police said, as a spate of violence marred the holiday.

Officers responding at about 1am on Wednesday (6am Irish time) to the mass shooting in a neighbourhood about 20 minutes east of the White House found a 10-year-old and 17-year-old among the victims, Metropolitan Police Department assistant chief Leslie Parsons said.

The victims, who were not publicly identified, were admitted to hospital with injuries not considered to be life-threatening, police said.

The shots were fired from a dark car seen driving through the Deanwood neighbourhood, Parsons said, calling the shooting targeted.

It was unclear if there was more than one gunman in the SUV and no arrests had been made, said police, who appealed to the public for information to help in their investigation.

The Washington shooting was the latest in a string of mass shootings over a violent holiday weekend.

Thirty people were shot, two fatally, at a block party in Baltimore early on Sunday.

Many of the shooting victims were children, authorities said.

On Monday night, a gunman in a bulletproof vest opened fire on the streets of Philadelphia, killing five people and wounding two boys, aged two and 13, before he surrendered, police said.

Three people were killed and eight others hurt when several men fired indiscriminately into a crowd of hundreds which had gathered in a Texas neighbourhood following a festival in the area, authorities said.

The shooting in the Fort Worth neighbourhood of Como happened late on Monday night, about two hours after the annual ComoFest ended.

And in Florida, a seven-year-old was killed in a shooting during an altercation between two groups gathered for Fourth of July celebrations along a causeway which crosses Tampa Bay, police said.

A man was also hit with gunfire but was expected to survive.

The child was declared dead at a hospital.