"The man attacked the couple with a sickle and they suffered bleeding injuries. They have been admitted to a private hospital," a senior police official told news agency PTI.
The assailant fled the scene, he said.
Visuals from a nearby CCTV showed the man attacking the couple from behind as they were seated on a two-wheeler. He flashed the sickle to those who dared to come close to saving the couple.
Sandeep and Madhavi, who belonged to different castes, were rushed to the hospital by local residents and passersby.
A newspaper report said the woman lost one of her hands in the grisly crime.
Some of them said the couple had got married a week ago. It was an inter-caste marriage, which her father was opposed to, they said.
"Sandeep was called by her father-in-law to a location in Erragadda here on the pretext of buying them some garments and the couple reached there... but he suddenly attacked them," one of Sandeep's friends told the media.
Last week, a Dalit Christian man was killed at Miryalguda in Nalgonda district in a case of alleged honour killing.
According to PTI, seven persons, including his father-in-law, who was opposed to the marriage, have been arrested. Shocking CCTV footage of the incident showed Pranay walking out of a hospital in Miryalguda with his pregnant wife when the assailant, who was later identified as Subhash Kumar Sharma, paced up and attacked him with a machete from behind, killing him instantaneously.