Two teenagers were taken into custody by officers following a stabbing in an alleyway.
The attack occurred in a passage between Hampton Way and Kent Road in Littlehampton at around 10pm on March 26.
Both male youths required hospital treatment after sustaining serious injuries.
Sussex Police confirmed that officers apprehended an 18-year-old man and a 17-year-old youth as part of their inquiries.
The older teenager was held on suspicion of causing serious physical harm and possessing a class B controlled substance.
The younger teenager was detained on suspicion of two counts of causing serious physical harm and possessing a class B drug with intent to supply.
Both have been granted bail while inquiries proceed.
Detective Inspector Lee Simmonds stated that officers are thoroughly examining the circumstances and acknowledged the concern felt by local residents.
He added that two people have been apprehended during the active investigation and members of the public with any knowledge are urged to get in touch if they have not already done so.
He further noted that additional officers have been deployed throughout the neighbourhood to reassure residents and support is being offered to those who were harmed.
Those with any information should call police on 101, quoting Operation Annscroft.
Anonymous reports can also be made to the independent charity Crimestoppers by telephoning 0800 555 111 or via their website.