The two-and-a-half-year-old girl was abducted from a religious event in west Delhi by two men on Friday night and raped before being dumped in a park near her home, relatives and police said.
In a separate incident on the other side of the city, the five-year-old was lured to a neighbour's house and raped by three men, a police officer told AFP.
The two attacks come as New Delhi grapples with a grim litany of sexual attacks against women – and in several recent cases, children – that have sparked outrage in India and abroad.
"We have launched a manhunt for the suspects. So far no one has been arrested," Pushpendra Kumar, West Delhi police chief, told AFP of the younger girl's case.
He said they found the younger child bleeding profusely several hours after she went missing and that tests showed she had been raped at least once.
Police have arrested three men in the case of the five-year-old victim whom tests showed was raped multiple times, after locals managed to catch her assailants and hand them over to the authorities.
A young girl stands on a ladder in a slum area where a four-year-old girl was allegedly raped, New Delhi, India Photo: EPA
"Her clothes were partially torn with blood spots all over them. Some locals saw her and she told them she was sexually assaulted," an officer from Anand Vihar police station told AFP on condition of anonymity.
"Some of the locals then barged into the house and caught them (the alleged perpetrators) before handing them over to us," the officer said.
Both girls are undergoing medical treatment but are believed to be out of danger.
The latest attacks come eight days after a four-year-old girl was allegedly raped and slashed with a blade before being abandoned by a railway track in the capital.
Police arrested a 25-year-old man in that attack, in which the young girl suffered severe internal injuries.
"When will Delhi wake up? Till when will girls continue to be brutalised in Indian capital. Gang rape of 2.5 year n 5 year old. Shameful," Delhi Commission for Women chairwomen Swati Maliwal tweeted Saturday.
Describing the assaults as "extremely shocking", Maliwal told Indian television station NDTV that violence against women had assumed "epidemic proportions" in Delhi.
Delhi Chief Minister Arvind Kejriwal expressed anguish over the rapes Saturday, terming them "shameful and worrying" on Twitter, but blamed his political opponent Prime Minister Narendra Modi's government for the deteriorating security situation in Delhi.
"Repeated rape of minors is shameful and worrying. Delhi police has completely failed to provide safety. What are PM n his LG (lieutenant governor) doing?," Kejriwal tweeted before heading to meet the victims in hospital.
Kejriwal and Modi's administration are jostling for control of the capital's police department, with Delhi city authorities saying they are unable to improve security for women.
They deflect the blame on to Modi's central government which controls Delhi's 84,000 police, the largest metropolitan police force in the world.
The fatal gang rape of a young student on a bus in Delhi in 2012 led to an outpouring of anger over frightening levels of violence against women.
